diff --git a/tools/validate.py b/tools/validate.py
index 139a3ee9150f0cf31ea48514403befb1fad957d6..5a9a34972aa6891295948551fcf348f99d90d1fb 100644
--- a/tools/validate.py
+++ b/tools/validate.py
@@ -21,10 +21,6 @@ import re
 
 import common
 
-import onnx
-from onnx import helper
-from onnx import TensorProto
-
 # Validation Flow:
 # 1. Generate input data
 # 2. Use mace_run to run model on phone.
@@ -198,6 +194,7 @@ def validate_onnx_model(platform, device_type, model_file, input_file,
                         mace_out_file, input_names, input_shapes,
                         output_names, output_shapes, validation_threshold,
                         input_data_types, backend):
+    import onnx
     if backend == "tensorflow":
         from onnx_tf.backend import prepare
         print "valivate on onnx tensorflow backend."
@@ -228,9 +225,9 @@ def validate_onnx_model(platform, device_type, model_file, input_file,
             out_shape[1], out_shape[2], out_shape[3] = \
                 out_shape[3], out_shape[1], out_shape[2]
         onnx_outputs.append(
-            helper.make_tensor_value_info(output_names[i],
-                                          TensorProto.FLOAT,
-                                          out_shape))
+            onnx.helper.make_tensor_value_info(output_names[i],
+                                               onnx.TensorProto.FLOAT,
+                                               out_shape))
     model.graph.output.extend(onnx_outputs)
     rep = prepare(model)