diff --git a/nn_meter/ir_converter/onnx_converter/converter.py b/nn_meter/ir_converter/onnx_converter/converter.py
index 17808e3e..b7002943 100644
--- a/nn_meter/ir_converter/onnx_converter/converter.py
+++ b/nn_meter/ir_converter/onnx_converter/converter.py
@@ -16,7 +16,7 @@ def __init__(self, model):
         self.graph = inferred_model.graph
 
         self.tensors = {}
-        for tensor in chain(self.graph.input, self.graph.value_info, self.graph.output):
+        for tensor in chain(self.graph.input, self.graph.value_info, self.graph.initializer, self.graph.output):
             self.tensors[tensor.name] = {
                 "shape": get_tensor_shape(tensor),
                 "inputs": [],
diff --git a/nn_meter/ir_converter/onnx_converter/utils.py b/nn_meter/ir_converter/onnx_converter/utils.py
index 172cc82b..e8b55733 100644
--- a/nn_meter/ir_converter/onnx_converter/utils.py
+++ b/nn_meter/ir_converter/onnx_converter/utils.py
@@ -2,8 +2,12 @@
 # Licensed under the MIT license.
 def get_tensor_shape(tensor):
     shape = []
-    for dim in tensor.type.tensor_type.shape.dim:
-        shape.append(dim.dim_value)
+    try:
+        for dim in tensor.type.tensor_type.shape.dim:
+            shape.append(dim.dim_value)
+    except AttributeError:
+        # initializer
+        shape += tensor.dims
     if len(shape) == 4:
         shape = [shape[0], shape[2], shape[3], shape[1]]
     return shape
diff --git a/nn_meter/utils/graph_tool.py b/nn_meter/utils/graph_tool.py
index 35947c3c..28b2324b 100644
--- a/nn_meter/utils/graph_tool.py
+++ b/nn_meter/utils/graph_tool.py
@@ -28,6 +28,9 @@ def node(self, name, inbound_nodes=None):
                 self.graph[node]["outbounds"].append(name)
 
     def refresh(self):
+        if len(self.graph) <= 1:
+            return
+
         last_remove_nodes_cnt = -1
         while True:
             for name in self.graph.keys():