diff --git a/components/layout/style/index.less b/components/layout/style/index.less
index dd82c34e61..9d81ec2239 100644
--- a/components/layout/style/index.less
+++ b/components/layout/style/index.less
@@ -38,7 +38,8 @@
 
   &-sider {
     flex: 0 0 200px;
-    transition: all .3s ease;
+    overflow: hidden;
+    transition: all .3s @ease-out;
     position: relative;
     background: @layout-sider-background;