diff --git a/packages/vant/docs/markdown/changelog.zh-CN-v4.md b/packages/vant/docs/markdown/changelog.zh-CN-v4.md
new file mode 100644
index 000000000..79c4bb471
--- /dev/null
+++ b/packages/vant/docs/markdown/changelog.zh-CN-v4.md
@@ -0,0 +1,11 @@
+# 更新日志
+
+## 更新内容
+
+### unreleased
+
+`2022-01-17`
+
+**Style**
+
+- Button: 默认圆角大小从 `2px` 调整为 `4px`
diff --git a/packages/vant/src/button/README.md b/packages/vant/src/button/README.md
index b11316edd..fd7ae7088 100644
--- a/packages/vant/src/button/README.md
+++ b/packages/vant/src/button/README.md
@@ -199,7 +199,7 @@ The component provides the following CSS variables, which can be used to customi
 | --van-button-warning-background | _var(--van-warning-color)_ | - |
 | --van-button-warning-border-color | _var(--van-warning-color)_ | - |
 | --van-button-border-width | _var(--van-border-width)_ | - |
-| --van-button-radius | _var(--van-radius-sm)_ | - |
+| --van-button-radius | _var(--van-radius-md)_ | - |
 | --van-button-round-radius | _var(--van-radius-max)_ | - |
 | --van-button-plain-background | _var(--van-white)_ | - |
 | --van-button-disabled-opacity | _var(--van-disabled-opacity)_ | - |
diff --git a/packages/vant/src/button/README.zh-CN.md b/packages/vant/src/button/README.zh-CN.md
index bd42f6a13..7e0cc1e1e 100644
--- a/packages/vant/src/button/README.zh-CN.md
+++ b/packages/vant/src/button/README.zh-CN.md
@@ -222,7 +222,7 @@ import type {
 | --van-button-warning-background   | _var(--van-orange)_           | -    |
 | --van-button-warning-border-color | _var(--van-orange)_           | -    |
 | --van-button-border-width         | _var(--van-border-width)_     | -    |
-| --van-button-radius               | _var(--van-radius-sm)_        | -    |
+| --van-button-radius               | _var(--van-radius-md)_        | -    |
 | --van-button-round-radius         | _var(--van-radius-max)_       | -    |
 | --van-button-plain-background     | _var(--van-white)_            | -    |
 | --van-button-disabled-opacity     | _var(--van-disabled-opacity)_ | -    |
diff --git a/packages/vant/src/button/index.less b/packages/vant/src/button/index.less
index fb6603ae4..c1b8c98c5 100644
--- a/packages/vant/src/button/index.less
+++ b/packages/vant/src/button/index.less
@@ -27,7 +27,7 @@
   --van-button-warning-background: var(--van-warning-color);
   --van-button-warning-border-color: var(--van-warning-color);
   --van-button-border-width: var(--van-border-width);
-  --van-button-radius: var(--van-radius-sm);
+  --van-button-radius: var(--van-radius-md);
   --van-button-round-radius: var(--van-radius-max);
   --van-button-plain-background: var(--van-white);
   --van-button-disabled-opacity: var(--van-disabled-opacity);