diff --git a/components/affix/index.en-US.md b/components/affix/index.en-US.md
index 202962a706..613a1a1d91 100644
--- a/components/affix/index.en-US.md
+++ b/components/affix/index.en-US.md
@@ -18,6 +18,7 @@ Please note that Affix should not cover other content on the page, especially wh
 |--------------|-----------------------|----------|--------------|
 | offsetTop    | Pixels to offset from top when calculating position of scroll | number | 0 |
 | offsetBottom | Pixels to offset from bottom when calculating position of scroll | number | - |
+| target | specifies the scrollable area dom node | () => HTMLElement | () => window |
 | onChange     | Callback when affix state is changed | Function(affixed) | - |
 
 **Note:** Children of `Affix` can not be `position: absolute`, but you can set `Affix` as `position: absolute`:
diff --git a/components/affix/index.zh-CN.md b/components/affix/index.zh-CN.md
index 7c1582c9a9..59ad33ac60 100644
--- a/components/affix/index.zh-CN.md
+++ b/components/affix/index.zh-CN.md
@@ -19,7 +19,7 @@ title: Affix
 |-------------|----------------|--------------------|--------------|
 | offsetTop    | 距离窗口顶部达到指定偏移量后触发   | number |         |
 | offsetBottom | 距离窗口底部达到指定偏移量后触发   | number |         |
-| target | 设置 `Affix` 需要监听其滚动事件的元素，值为一个返回对应 DOM 元素的函数 | Function | () => window |
+| target | 设置 `Affix` 需要监听其滚动事件的元素，值为一个返回对应 DOM 元素的函数 | () => HTMLElement | () => window |
 | onChange | 固定状态改变时触发的回调函数   | Function(affixed) | 无        |
 
 **注意：**`Affix` 内的元素不要使用绝对定位，如需要绝对定位的效果，可以直接设置 `Affix` 为绝对定位：
diff --git a/components/back-top/index.en-US.md b/components/back-top/index.en-US.md
index 9d3874d171..30ba06b07a 100644
--- a/components/back-top/index.en-US.md
+++ b/components/back-top/index.en-US.md
@@ -22,4 +22,4 @@ Property | Description | Type | Default
 -----|-----|-----|------
 visibilityHeight | the `BackTop` button will not show until the scroll height reaches this value | number | 400
 onClick | a callback function, which can be executed when you click the button | Function | -
-
+target | specifies the scrollable area dom node | () => HTMLElement | () => window
diff --git a/components/back-top/index.zh-CN.md b/components/back-top/index.zh-CN.md
index 2d227ca44f..3ad518b334 100644
--- a/components/back-top/index.zh-CN.md
+++ b/components/back-top/index.zh-CN.md
@@ -22,3 +22,4 @@ title: BackTop
 |-------------|----------------|--------------------|--------------|
 | visibilityHeight    | 滚动高度达到此参数值才出现 `BackTop`   | number | 400        |
 | onClick | 点击按钮的回调函数   | Function | -        |
+| target | 设置需要监听其滚动事件的元素，值为一个返回对应 DOM 元素的函数 | Function | () => window |