diff --git a/paddle/operators/feed_op.h b/paddle/operators/feed_op.h
index 47344e309ce381e25a51b7162d8b5e28ccec09cf..e406d22209dc5597f232918634634f3cf3b44e4a 100644
--- a/paddle/operators/feed_op.h
+++ b/paddle/operators/feed_op.h
@@ -31,6 +31,9 @@ class FeedKernel : public framework::OpKernel<T> {
         g_feed_variable->Get<std::vector<framework::Tensor>>();
     int col = ctx.template Attr<int>("col");
     PADDLE_ENFORCE_GT(tensors.size(), static_cast<size_t>(col));
+    // TODO(qijun):
+    //   check tensors[col].dims() with attribute,
+    //   except the first dimenson.
     out->CopyFrom<T>(tensors[col], ctx.GetPlace());
   }
 };