diff --git a/x2paddle/op_mapper/onnx_op_mapper.py b/x2paddle/op_mapper/onnx_op_mapper.py
index a1b15b93901de54d546e022781eb31080e6898b4..90b50ff652559baa0a68193e0161f8bbc6ffc22e 100644
--- a/x2paddle/op_mapper/onnx_op_mapper.py
+++ b/x2paddle/op_mapper/onnx_op_mapper.py
@@ -1231,10 +1231,11 @@ class ONNXOpMapper(OpMapper):
     def ConvTranspose(self, node):
         val_x = self.graph.get_input_node(node, idx=0, copy=True)
         val_w = self.graph.get_input_node(node, idx=1, copy=True)
-        val_b = self.graph.get_input_node(node, idx=2, copy=True)
-
+        val_b = None
+        if len(node.layer.input)>2:
+            val_b = self.graph.get_input_node(node, idx=2, copy=True)
+            self.omit_nodes.append(val_b.layer_name)
         self.omit_nodes.append(val_w.layer_name)
-        self.omit_nodes.append(val_b.layer_name)
 
         val_y = self.graph.get_node(node.layer.output[0], copy=True)
 
@@ -1272,7 +1273,7 @@ class ONNXOpMapper(OpMapper):
             'dilation': dilations,
             'groups': num_groups,
             'param_attr': string(val_w.layer_name),
-            'bias_attr': string(val_b.layer_name),
+            'bias_attr': None if val_b is None else string(val_b.layer_name),
             'name': string(node.layer_name),
         }
         node.fluid_code.add_layer(fluid_op,