diff --git a/paddle/framework/operator.h b/paddle/framework/operator.h
index 32362503664eb217cba0f2bc8cfc8434cc9248a1..a2544f1dcd70b05e5550f8743a61a03335c549fb 100644
--- a/paddle/framework/operator.h
+++ b/paddle/framework/operator.h
@@ -290,12 +290,12 @@ class ExecutionContext {
     return device_context_;
   }
 
-  //! Get variables vector with same input name.
+  //! Get actual name vector for this input.
   const std::vector<std::string>& Inputs(const std::string& name) const {
     return op_.Inputs(name);
   }
 
-  //! Get variables vector with same output name.
+  //! Get actual name vector for this output.
   const std::vector<std::string>& Outputs(const std::string& name) const {
     return op_.Outputs(name);
   }
diff --git a/paddle/operators/nccl_op.cc b/paddle/operators/nccl_op.cc
index 3744d1b4707be68185565d8e94f2a165ec42739b..d39cb2fcf9cc205edf86f8ab1d5e04b5672e00f6 100644
--- a/paddle/operators/nccl_op.cc
+++ b/paddle/operators/nccl_op.cc
@@ -30,6 +30,11 @@ class NCCLInitOp : public framework::OperatorBase {
                             "Can not find variable '%s' in the scope.", name);
     std::vector<int> gpus = Attr<std::vector<int>>("gpus");
     PADDLE_ENFORCE(!gpus.empty(), "Attr(gpus) should not be empty.");
+
+    if (scope.FindVar(name) == nullptr) {
+      PADDLE_THROW("Output(Communicator) is needed for ncclInit operator.");
+    }
+
     platform::Communicator *comm =
         scope.FindVar(name)->GetMutable<platform::Communicator>();
     comm->InitAll(gpus);
diff --git a/paddle/operators/nccl_op.cu b/paddle/operators/nccl_op.cu
index f8b3b8a8baf77a1091629969b56ace826cdbd371..86dee8ee8e1c1a1041d6bc9fa515d669a9c4e466 100644
--- a/paddle/operators/nccl_op.cu
+++ b/paddle/operators/nccl_op.cu
@@ -9,7 +9,6 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License. */
 
-#define EIGEN_USE_GPU
 #include <functional>
 
 #include "paddle/framework/lod_tensor.h"
@@ -60,7 +59,7 @@ class NCCLAllReduceKernel : public framework::OpKernel<T> {
     } else if (reduction == "ncclProd") {
       reduction_op_ = ncclProd;
     } else {
-      PADDLE_ENFORCE(false, "Invalid reduction. default ncclSum.");
+      PADDLE_THROW("Invalid reduction. default ncclSum.");
     }
 
     auto* comm = ctx.Input<Communicator>("Communicator");
@@ -113,7 +112,7 @@ class NCCLReduceKernel : public framework::OpKernel<T> {
     } else if (reduction == "ncclProd") {
       reduction_op_ = ncclProd;
     } else {
-      PADDLE_ENFORCE(false, "Invalid reduction. default ncclSum.");
+      PADDLE_THROW("Invalid reduction. default ncclSum.");
     }
 
     int root = ctx.Attr<int>("root");
diff --git a/paddle/operators/nccl_op_test.cu b/paddle/operators/nccl_op_test.cu
index 63a286f602024e87a2589286d30102290abb3b30..80c50a28a9e5d560fc693c518b9e62091ddc5724 100644
--- a/paddle/operators/nccl_op_test.cu
+++ b/paddle/operators/nccl_op_test.cu
@@ -12,8 +12,6 @@
    See the License for the specific language governing permissions and
    limitations under the License. */
 
-#define EIGEN_USE_GPU
-
 #include <glog/logging.h>
 #include <gtest/gtest.h>
 #include <algorithm>
@@ -193,7 +191,7 @@ TEST_F(NCCLTester, ncclAllReduceOp) {
   }
 }
 
-// ncclAReduceOp with desc
+// ncclReduceOp with desc
 TEST_F(NCCLTester, ncclReduceOp) {
   std::unique_ptr<f::OpDescBind> op2(new f::OpDescBind);
   const int kRoot = 0;
@@ -201,7 +199,7 @@ TEST_F(NCCLTester, ncclReduceOp) {
   op2->SetInput("X", {"st"});
   op2->SetInput("Communicator", {"comm"});
   op2->SetOutput("Out", {"rt"});
-  op2->SetAttr("root", {kRoot});
+  op2->SetAttr("root", kRoot);
 
   std::vector<f::Scope *> dev_scopes;
 
@@ -241,7 +239,7 @@ TEST_F(NCCLTester, ncclReduceOp) {
   }
 }
 
-// // ncclBcastOp with desc
+// ncclBcastOp with desc
 TEST_F(NCCLTester, ncclBcastOp) {
   std::unique_ptr<f::OpDescBind> op2(new f::OpDescBind);
   const int kRoot = 5;
@@ -249,7 +247,7 @@ TEST_F(NCCLTester, ncclBcastOp) {
   op2->SetInput("X", {"st"});
   op2->SetInput("Communicator", {"comm"});
   op2->SetOutput("Out", {"rt"});
-  op2->SetAttr("root", {kRoot});
+  op2->SetAttr("root", kRoot);
 
   std::vector<f::Scope *> dev_scopes;