diff --git a/src/collapse/index.js b/src/collapse/index.ts
similarity index 62%
rename from src/collapse/index.js
rename to src/collapse/index.ts
index 4b01579a7..9678fb4a9 100644
--- a/src/collapse/index.js
+++ b/src/collapse/index.ts
@@ -1,3 +1,3 @@
 /* istanbul ignore file */
-export { default as NCollapse } from './src/Collapse.js'
+export { default as NCollapse } from './src/Collapse'
 export { default as NCollapseItem } from './src/CollapseItem.vue'
diff --git a/src/collapse/src/Collapse.js b/src/collapse/src/Collapse.ts
similarity index 51%
rename from src/collapse/src/Collapse.js
rename to src/collapse/src/Collapse.ts
index d8acba3cb..157a3a9fa 100644
--- a/src/collapse/src/Collapse.js
+++ b/src/collapse/src/Collapse.ts
@@ -1,27 +1,37 @@
-import { computed, h, markRaw, defineComponent } from 'vue'
+import {
+  computed,
+  h,
+  defineComponent,
+  PropType,
+  toRef,
+  reactive,
+  provide
+} from 'vue'
 import { intersection } from 'lodash-es'
 import { useTheme } from '../../_mixins'
 import { call, warn } from '../../_utils'
 import { collapseLight } from '../styles'
-import style from './styles/index.cssr.js'
+import type { CollapseThemeVars } from '../styles'
+import style from './styles/index.cssr'
+
+export interface NCollapseInjection {
+  arrowPlacement: 'left' | 'right'
+  displayDirective: 'if' | 'show'
+  expandedNames: string | string[]
+  collectedItemNames: string[]
+  toggleItem(collapse: boolean, name: string, event: MouseEvent): void
+}
 
 export default defineComponent({
   name: 'Collapse',
-  provide () {
-    return {
-      NCollapse: this
-    }
-  },
   props: {
     ...useTheme.props,
     expandedNames: {
-      type: [Array, String],
+      type: [Array, String] as PropType<string | string[]>,
       default: undefined
     },
     arrowPlacement: {
-      validator (value) {
-        return ['left', 'right'].includes(value)
-      },
+      type: String as PropType<'left' | 'right'>,
       default: 'left'
     },
     accordion: {
@@ -29,9 +39,7 @@ export default defineComponent({
       default: false
     },
     displayDirective: {
-      validator (value) {
-        return ['if', 'show'].includes(value)
-      },
+      type: String as PropType<'if' | 'show'>,
       default: 'if'
     },
     onItemHeaderClick: {
@@ -40,12 +48,13 @@ export default defineComponent({
     },
     // eslint-disable-next-line vue/prop-name-casing
     'onUpdate:expandedNames': {
-      type: Function,
+      type: Function as PropType<(expandedNames: string[]) => void>,
       default: undefined
     },
     // deprecated
     onExpandedNamesChange: {
-      validator () {
+      type: Function,
+      validator: () => {
         if (__DEV__) {
           warn(
             'collapse',
@@ -58,15 +67,72 @@ export default defineComponent({
     }
   },
   setup (props) {
-    const themeRef = useTheme(
+    const collectedItemNames: string[] = []
+    const themeRef = useTheme<CollapseThemeVars>(
       'Collapse',
       'Collapse',
       style,
       collapseLight,
       props
     )
+    function doUpdateExpandedNames (names: string[]) {
+      const {
+        'onUpdate:expandedNames': updateExpandedNames,
+        onExpandedNamesChange
+      } = props
+      if (updateExpandedNames) call(updateExpandedNames, names)
+      if (onExpandedNamesChange) call(onExpandedNamesChange, names)
+    }
+    function doItemHeaderClick (info: {
+      name: string
+      expanded: boolean
+      event: MouseEvent
+    }) {
+      const { onItemHeaderClick } = props
+      if (onItemHeaderClick) call(onItemHeaderClick, info)
+    }
+    function toggleItem (collapse: boolean, name: string, event: MouseEvent) {
+      const { accordion, expandedNames } = props
+      if (accordion) {
+        if (collapse) {
+          doUpdateExpandedNames([name])
+          doItemHeaderClick({ name, expanded: true, event })
+        } else {
+          doUpdateExpandedNames([])
+          doItemHeaderClick({ name, expanded: false, event })
+        }
+      } else {
+        if (!Array.isArray(expandedNames)) {
+          doUpdateExpandedNames([name])
+          doItemHeaderClick({ name, expanded: true, event })
+        } else {
+          const activeNames = intersection(expandedNames, collectedItemNames)
+          const index = activeNames.findIndex(
+            (activeName) => name === activeName
+          )
+          if (~index) {
+            activeNames.splice(index, 1)
+            doUpdateExpandedNames(activeNames)
+            doItemHeaderClick({ name, expanded: false, event })
+          } else {
+            activeNames.push(name)
+            doUpdateExpandedNames(activeNames)
+            doItemHeaderClick({ name, expanded: true, event })
+          }
+        }
+      }
+    }
+    provide<NCollapseInjection>(
+      'NCollapse',
+      reactive({
+        arrowPlacement: toRef(props, 'arrowPlacement'),
+        displayDirective: toRef(props, 'displayDirective'),
+        expandedNames: toRef(props, 'expandedNames'),
+        collectedItemNames,
+        toggleItem
+      })
+    )
     return {
-      collectedItemNames: markRaw([]),
       mergedTheme: themeRef,
       cssVars: computed(() => {
         const {
@@ -94,53 +160,6 @@ export default defineComponent({
       })
     }
   },
-  methods: {
-    doUpdateExpandedNames (...args) {
-      const {
-        'onUpdate:expandedNames': updateExpandedNames,
-        onExpandedNamesChange
-      } = this
-      if (updateExpandedNames) call(updateExpandedNames, ...args)
-      if (onExpandedNamesChange) call(onExpandedNamesChange, ...args)
-    },
-    doItemHeaderClick (...args) {
-      const { onItemHeaderClick } = this
-      if (onItemHeaderClick) call(onItemHeaderClick, ...args)
-    },
-    toggleItem (collapse, name, event) {
-      if (this.accordion) {
-        if (collapse) {
-          this.doUpdateExpandedNames([name])
-          this.doItemHeaderClick({ name, expanded: true, event })
-        } else {
-          this.doUpdateExpandedNames([])
-          this.doItemHeaderClick({ name, expanded: false, event })
-        }
-      } else {
-        if (!Array.isArray(this.expandedNames)) {
-          this.doUpdateExpandedNames([name])
-          this.doItemHeaderClick({ name, expanded: true, event })
-        } else {
-          const activeNames = intersection(
-            this.expandedNames,
-            this.collectedItemNames
-          )
-          const index = activeNames.findIndex(
-            (activeName) => name === activeName
-          )
-          if (~index) {
-            activeNames.splice(index, 1)
-            this.doUpdateExpandedNames(activeNames)
-            this.doItemHeaderClick({ name, expanded: false, event })
-          } else {
-            activeNames.push(name)
-            this.doUpdateExpandedNames(activeNames)
-            this.doItemHeaderClick({ name, expanded: true, event })
-          }
-        }
-      }
-    }
-  },
   render () {
     return h(
       'div',
diff --git a/src/collapse/src/CollapseItem.vue b/src/collapse/src/CollapseItem.vue
index 14cf4d3cb..6a0b02f56 100644
--- a/src/collapse/src/CollapseItem.vue
+++ b/src/collapse/src/CollapseItem.vue
@@ -36,12 +36,13 @@
   </div>
 </template>
 
-<script>
-import { toRef, defineComponent } from 'vue'
+<script lang="ts">
+import { toRef, defineComponent, PropType, inject, computed } from 'vue'
 import { ChevronRightIcon as ArrowIcon } from '../../_base/icons'
 import { NBaseIcon } from '../../_base'
 import { useInjectionCollection } from '../../_utils/composable'
-import NCollapseItemContent from './CollapseItemContent.js'
+import NCollapseItemContent from './CollapseItemContent'
+import { NCollapseInjection } from './Collapse'
 
 export default defineComponent({
   name: 'CollapseItem',
@@ -50,60 +51,56 @@ export default defineComponent({
     NCollapseItemContent,
     ArrowIcon
   },
-  inject: {
-    NCollapse: {
-      default: null
-    }
-  },
   props: {
     title: {
       type: String,
       default: undefined
     },
     name: {
-      type: [String, Number],
+      type: String,
       default: undefined
     },
     displayDirective: {
-      validator (value) {
-        return ['if', 'show'].includes(value)
-      },
+      type: String as PropType<'if' | 'show' | undefined>,
       default: undefined
     }
   },
   setup (props) {
+    const NCollapse = inject<NCollapseInjection>(
+      'NCollapse'
+    ) as NCollapseInjection
     useInjectionCollection(
       'NCollapse',
       'collectedItemNames',
       toRef(props, 'name')
     )
-  },
-  computed: {
-    mergedDisplayDirective () {
-      const { displayDirective, NCollapse } = this
-      if (displayDirective) {
-        return displayDirective
-      } else {
-        return NCollapse.displayDirective
-      }
-    },
-    arrowPlacement () {
-      return this.NCollapse.arrowPlacement
-    },
-    collapsed () {
-      const { NCollapse } = this
-      if (NCollapse && Array.isArray(NCollapse.expandedNames)) {
-        const itemName = this.name
-        return !~NCollapse.expandedNames.findIndex((name) => name === itemName)
+    const collapsedRef = computed<boolean>(() => {
+      const { expandedNames } = NCollapse
+      if (Array.isArray(expandedNames)) {
+        const { name } = props
+        return !~expandedNames.findIndex(
+          (expandedName) => expandedName === name
+        )
       }
       return true
-    }
-  },
-  methods: {
-    handleClick (e) {
-      const { NCollapse } = this
-      if (NCollapse) {
-        NCollapse.toggleItem(this.collapsed, this.name, e)
+    })
+    return {
+      collapsed: collapsedRef,
+      mergedDisplayDirective: computed<'if' | 'show'>(() => {
+        const { displayDirective } = props
+        if (displayDirective) {
+          return displayDirective
+        } else {
+          return NCollapse.displayDirective
+        }
+      }),
+      arrowPlacement: computed<'left' | 'right'>(() => {
+        return NCollapse.arrowPlacement
+      }),
+      handleClick (e: MouseEvent) {
+        if (NCollapse) {
+          NCollapse.toggleItem(collapsedRef.value, props.name, e)
+        }
       }
     }
   }
diff --git a/src/collapse/src/CollapseItemContent.js b/src/collapse/src/CollapseItemContent.ts
similarity index 86%
rename from src/collapse/src/CollapseItemContent.js
rename to src/collapse/src/CollapseItemContent.ts
index 25bccfc37..54bf0bc92 100644
--- a/src/collapse/src/CollapseItemContent.js
+++ b/src/collapse/src/CollapseItemContent.ts
@@ -1,4 +1,10 @@
-import { h, withDirectives, vShow, defineComponent } from 'vue'
+import {
+  h,
+  withDirectives,
+  vShow,
+  defineComponent,
+  DirectiveArguments
+} from 'vue'
 import { NFadeInExpandTransition } from '../../_base'
 
 export default defineComponent({
@@ -22,7 +28,7 @@ export default defineComponent({
   render () {
     const { show, displayDirective } = this
     const useVShow = displayDirective === 'show'
-    const directives = useVShow ? [[vShow, show]] : []
+    const directives: DirectiveArguments = useVShow ? [[vShow, show]] : []
     return h(NFadeInExpandTransition, null, {
       default: () =>
         useVShow || show
diff --git a/src/collapse/src/styles/index.cssr.js b/src/collapse/src/styles/index.cssr.js
deleted file mode 100644
index 3b069227b..000000000
--- a/src/collapse/src/styles/index.cssr.js
+++ /dev/null
@@ -1,91 +0,0 @@
-import { c, cB, cE, cM } from '../../../_utils/cssr'
-import fadeInHeightExpandTransition from '../../../_styles/transitions/fade-in-height-expand'
-
-// vars:
-// --font-size
-// --bezier
-// --text-color
-// --divider-color
-// --title-font-size
-// --title-text-color
-// --title-font-weight
-// --arrow-color
-export default cB('collapse', {
-  width: '100%'
-}, [
-  cB('collapse-item', `
-    overflow: hidden;
-    font-size: var(--font-size);
-    transition: border-color .3s var(--bezier);
-    margin-top: 16px;
-  `, [
-    c('&:first-child', {
-      marginTop: 0
-    }),
-    c('&:first-child >', [
-      cE('header', {
-        paddingTop: 0
-      })
-    ]),
-    cM('left-arrow-placement', [
-      cE('header', [
-        cB('collapse-item-arrow', {
-          marginRight: '4px'
-        })
-      ])
-    ]),
-    cM('right-arrow-placement', [
-      cE('header', [
-        cB('collapse-item-arrow', {
-          marginLeft: '4px'
-        })
-      ])
-    ]),
-    cB('collapse-item', {
-      marginLeft: '32px'
-    }),
-    cE('content-wrapper', {
-      overflow: 'hidden'
-    }, [
-      fadeInHeightExpandTransition({ duration: '0.15s' })
-    ]),
-    cM('active', [
-      cE('header', [
-        cM('active', [
-          cB('collapse-item-arrow', {
-            transform: 'rotate(90deg)'
-          })
-        ])
-      ])
-    ]),
-    c('&:not(:first-child)', {
-      borderTop: '1px solid var(--divider-color)'
-    }),
-    cE('header', `
-      font-size: var(--title-font-size);
-      display: flex;
-      flex-wrap: nowrap;
-      align-items: center;
-      font-weight: var(--title-font-weight);
-      transition: color .3s var(--bezier);
-      position: relative;
-      cursor: pointer;
-      padding: 16px 0 0 0;
-      color: var(--title-text-color);
-    `, [
-      cB('collapse-item-arrow', `
-        display: flex;
-        transition:
-          transform .15s var(--bezier),
-          color .3s var(--bezier);
-        font-size: 18px;
-        color: var(--arrow-color);
-      `)
-    ]),
-    cE('content-inner', `
-      transition: color .3s var(--bezier);
-      padding-top: 16px;
-      color: var(--text-color);
-    `)
-  ])
-])
diff --git a/src/collapse/src/styles/index.cssr.ts b/src/collapse/src/styles/index.cssr.ts
new file mode 100644
index 000000000..95c6e993d
--- /dev/null
+++ b/src/collapse/src/styles/index.cssr.ts
@@ -0,0 +1,111 @@
+import { c, cB, cE, cM } from '../../../_utils/cssr'
+import fadeInHeightExpandTransition from '../../../_styles/transitions/fade-in-height-expand'
+
+// vars:
+// --font-size
+// --bezier
+// --text-color
+// --divider-color
+// --title-font-size
+// --title-text-color
+// --title-font-weight
+// --arrow-color
+export default cB(
+  'collapse',
+  {
+    width: '100%'
+  },
+  [
+    cB(
+      'collapse-item',
+      `
+    overflow: hidden;
+    font-size: var(--font-size);
+    transition: border-color .3s var(--bezier);
+    margin-top: 16px;
+  `,
+      [
+        c('&:first-child', {
+          marginTop: 0
+        }),
+        c('&:first-child >', [
+          cE('header', {
+            paddingTop: 0
+          })
+        ]),
+        cM('left-arrow-placement', [
+          cE('header', [
+            cB('collapse-item-arrow', {
+              marginRight: '4px'
+            })
+          ])
+        ]),
+        cM('right-arrow-placement', [
+          cE('header', [
+            cB('collapse-item-arrow', {
+              marginLeft: '4px'
+            })
+          ])
+        ]),
+        cB('collapse-item', {
+          marginLeft: '32px'
+        }),
+        cE(
+          'content-wrapper',
+          {
+            overflow: 'hidden'
+          },
+          [fadeInHeightExpandTransition({ duration: '0.15s' })]
+        ),
+        cM('active', [
+          cE('header', [
+            cM('active', [
+              cB('collapse-item-arrow', {
+                transform: 'rotate(90deg)'
+              })
+            ])
+          ])
+        ]),
+        c('&:not(:first-child)', {
+          borderTop: '1px solid var(--divider-color)'
+        }),
+        cE(
+          'header',
+          `
+      font-size: var(--title-font-size);
+      display: flex;
+      flex-wrap: nowrap;
+      align-items: center;
+      font-weight: var(--title-font-weight);
+      transition: color .3s var(--bezier);
+      position: relative;
+      cursor: pointer;
+      padding: 16px 0 0 0;
+      color: var(--title-text-color);
+    `,
+          [
+            cB(
+              'collapse-item-arrow',
+              `
+        display: flex;
+        transition:
+          transform .15s var(--bezier),
+          color .3s var(--bezier);
+        font-size: 18px;
+        color: var(--arrow-color);
+      `
+            )
+          ]
+        ),
+        cE(
+          'content-inner',
+          `
+      transition: color .3s var(--bezier);
+      padding-top: 16px;
+      color: var(--text-color);
+    `
+        )
+      ]
+    )
+  ]
+)
diff --git a/src/collapse/styles/dark.js b/src/collapse/styles/dark.ts
similarity index 74%
rename from src/collapse/styles/dark.js
rename to src/collapse/styles/dark.ts
index 48bfbabbf..b848b5776 100644
--- a/src/collapse/styles/dark.js
+++ b/src/collapse/styles/dark.ts
@@ -1,9 +1,11 @@
 import { commonDark } from '../../_styles/new-common'
+import type { ThemeCommonVars } from '../../_styles/new-common'
+import type { CollapseThemeVars } from './light'
 
 export default {
   name: 'Collapse',
   common: commonDark,
-  self (vars) {
+  self (vars: ThemeCommonVars): CollapseThemeVars {
     const {
       fontWeight,
       textColor1,
diff --git a/src/collapse/styles/index.js b/src/collapse/styles/index.js
deleted file mode 100644
index c97adbf3c..000000000
--- a/src/collapse/styles/index.js
+++ /dev/null
@@ -1,2 +0,0 @@
-export { default as collapseDark } from './dark.js'
-export { default as collapseLight } from './light.js'
diff --git a/src/collapse/styles/index.ts b/src/collapse/styles/index.ts
new file mode 100644
index 000000000..16c4aecee
--- /dev/null
+++ b/src/collapse/styles/index.ts
@@ -0,0 +1,3 @@
+export { default as collapseDark } from './dark'
+export { default as collapseLight } from './light'
+export type { CollapseThemeVars } from './light'
diff --git a/src/collapse/styles/light.js b/src/collapse/styles/light.ts
similarity index 68%
rename from src/collapse/styles/light.js
rename to src/collapse/styles/light.ts
index 1eca0ced9..c0a9543b7 100644
--- a/src/collapse/styles/light.js
+++ b/src/collapse/styles/light.ts
@@ -1,9 +1,10 @@
 import { commonLight } from '../../_styles/new-common'
+import type { ThemeCommonVars } from '../../_styles/new-common'
 
-export default {
+const collapseLight = {
   name: 'Collapse',
   common: commonLight,
-  self (vars) {
+  self (vars: ThemeCommonVars) {
     const {
       fontWeight,
       textColor1,
@@ -22,3 +23,6 @@ export default {
     }
   }
 }
+
+export default collapseLight
+export type CollapseThemeVars = ReturnType<typeof collapseLight.self>