diff --git a/x2paddle/core/graph.py b/x2paddle/core/graph.py
index 04a6e6e579d5ce25b77478446bd3f3977e8a7385..0d7eb76b2833ffed6b3f16bd58c1d3531d4cbdc9 100644
--- a/x2paddle/core/graph.py
+++ b/x2paddle/core/graph.py
@@ -43,23 +43,23 @@ class Graph(object):
         self.model = model
 
     def build(self):
-        self._make_input_nodes()
-        self._make_output_nodes()
-        self._get_topo_sort()
+        self.get_input_nodes()
+        self.get_output_nodes()
+        self.get_topo_sort()
 
-    def _make_input_nodes(self):
+    def get_input_nodes(self):
         for name, node in self.node_map.items():
             name = name.replace('/', '_').replace('-', '_')
             if len(node.inputs) == 0:
                 self.input_nodes.append(name)
 
-    def _make_output_nodes(self):
+    def get_output_nodes(self):
         for name, node in self.node_map.items():
             name = name.replace('/', '_').replace('-', '_')
             if len(node.outputs) == 0:
                 self.output_nodes.append(name)
 
-    def _get_topo_sort(self):
+    def get_topo_sort(self):
         num_inputs = dict()
         for name, node in self.node_map.items():
             num_inputs[name] = len(node.inputs)
diff --git a/x2paddle/core/op_mapper.py b/x2paddle/core/op_mapper.py
index 6ba557bdf5865043747a20806e8ab8da021ff822..dacf4dd37c9411fb3d48888c9ea22ecd25e86956 100644
--- a/x2paddle/core/op_mapper.py
+++ b/x2paddle/core/op_mapper.py
@@ -11,7 +11,7 @@
 # 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.
-
+from paddle.fluid.proto import framework_pb2
 from x2paddle.core.util import *
 import inspect
 import os
diff --git a/x2paddle/core/util.py b/x2paddle/core/util.py
index 45048b82c2ae9fa143ab4140600a79ef209cc574..54524b8fd5e8e678c80982abb59398241bfc0f70 100644
--- a/x2paddle/core/util.py
+++ b/x2paddle/core/util.py
@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from paddle.fluid.proto import framework_pb2
 import paddle.fluid as fluid
 import numpy
 import math