diff --git a/components/input/style/search-input.less b/components/input/style/search-input.less
index a4bf3b0857..909d6beffe 100644
--- a/components/input/style/search-input.less
+++ b/components/input/style/search-input.less
@@ -30,6 +30,7 @@
 }
 
 // code blow is keeped for compatibility
+// for this demo: http://1x.ant.design/components/select/#components-select-demo-search-box
 // do not delete until 3.x
 .@{ant-prefix}-search-input-wrapper {
   display: inline-block;