diff --git a/paddle/framework/backward.cc b/paddle/framework/backward.cc
index 2d9efdd51142b5a00a85f07a806359e179c7b32c..7e111551d907c00995be649df0dabd0836e051d7 100644
--- a/paddle/framework/backward.cc
+++ b/paddle/framework/backward.cc
@@ -86,8 +86,6 @@ static std::shared_ptr<OperatorBase> BackwardImpl(
     // travesal subnet/op
     for (auto it = forwardNet.ops_.end(); it != forwardNet.ops_.begin(); --it) {
       auto fwd = *it;
-      // for (auto& fwd : forwardNet.ops_) {
-      // auto bwd = Backward(*fwd, no_grad_names);
       auto bwd = Backward(*fwd, no_grad_names);
       net->AddOp(bwd);
       for (size_t i = 0; i < bwd->outputs_.size(); ++i) {
diff --git a/paddle/framework/backward_test.cc b/paddle/framework/backward_test.cc
index 54acc4759961b2c17cfd41c6c1f405b2d0a3e45c..ada7c7068298249b932287f925cb55bb36ee75e9 100644
--- a/paddle/framework/backward_test.cc
+++ b/paddle/framework/backward_test.cc
@@ -63,10 +63,10 @@ class FcOp : public NetOp {
  public:
   void Init() override {
     AddOp(OpRegistry::CreateOp("mul", {Input("X"), Input("W")},
-                               {Output("before_act")}, {}));
+                               {Output("mul_out")}, {}));
     auto b_name = Input("b");
     if (b_name != EMPTY_VAR_NAME()) {
-      AddOp(OpRegistry::CreateOp("rowwise_add", {Output("before_act"), b_name},
+      AddOp(OpRegistry::CreateOp("rowwise_add", {Output("mul_out"), b_name},
                                  {Output("before_act")}, {}));
     }
     AddOp(OpRegistry::CreateOp("sigmoid", {Output("before_act")},
@@ -82,6 +82,7 @@ class FcOpMaker : public OpProtoAndCheckerMaker {
     AddInput("X", "x");
     AddInput("W", "w");
     AddInput("b", "b");
+    AddOutput("mul_out", "mul output").SetTemporary();
     AddOutput("before_act", "before act").SetTemporary();
     AddOutput("Out", "");
     AddComment("");
@@ -140,6 +141,7 @@ TEST(Backward, simple_op_grad) {
   auto fwd = f::OpRegistry::CreateOp("rowwise_add", {"X", "b"}, {"Out"}, {});
   ASSERT_NE(fwd, nullptr);
   auto gop = f::OpRegistry::CreateGradOp(*fwd);
+  LOG(INFO) << gop->DebugString();
   ASSERT_EQ(1UL, gop->inputs_.size());
   ASSERT_EQ("Out" + f::OperatorBase::GRAD_VAR_SUFFIX(), gop->inputs_[0]);
   ASSERT_EQ("rowwise_add_grad", gop->type_);
@@ -151,10 +153,18 @@ TEST(Backward, simple_op_grad) {
   //  LOG(INFO) << gop->Output("X" + "@GRAD");
 }
 
+TEST(Backward, simple_net_grad) {
+  auto fwd = f::OpRegistry::CreateOp("rowwise_add", {"X", "b"}, {"Out"}, {});
+  ASSERT_NE(fwd, nullptr);
+  auto gop = f::Backward(*fwd, {});
+  LOG(INFO) << gop->DebugString();
+}
+
 TEST(Backward, net_fc_backward_normal) {
   std::shared_ptr<f::OperatorBase> fwd =
       f::OpRegistry::CreateOp("fc", {"X", "w", "b"}, {"out"}, {});
   ASSERT_NE(fwd, nullptr);
+  LOG(INFO) << fwd->DebugString();
   std::shared_ptr<f::OperatorBase> gop = f::Backward(*fwd, {});
   ASSERT_TRUE(gop->IsNetOp());
   auto net = static_cast<f::NetOp *>(gop.get());