diff --git a/components/tag/demo/control.md b/components/tag/demo/control.md
index 4107b2360a..345ee20b66 100644
--- a/components/tag/demo/control.md
+++ b/components/tag/demo/control.md
@@ -66,7 +66,7 @@ class EditableTagGroup extends React.Component {
               {isLongTag ? `${tag.slice(0, 20)}...` : tag}
             </Tag>
           );
-          return isLongTag ? <Tooltip title={tag}>{tagElem}</Tooltip> : tagElem;
+          return isLongTag ? <Tooltip title={tag} key={tag}>{tagElem}</Tooltip> : tagElem;
         })}
         {inputVisible && (
           <Input