diff --git a/pyinfinitensor/src/pyinfinitensor/onnx.py b/pyinfinitensor/src/pyinfinitensor/onnx.py
index c98fa7cf..8322ea26 100644
--- a/pyinfinitensor/src/pyinfinitensor/onnx.py
+++ b/pyinfinitensor/src/pyinfinitensor/onnx.py
@@ -2,7 +2,7 @@
 from onnx import ModelProto, TensorProto, NodeProto, AttributeProto, TensorShapeProto
 from onnx.helper import make_node
 from onnx.shape_inference import infer_shapes
-from typing import Dict, List, Any
+from typing import Dict, List, Any, Tuple
 from functools import reduce
 
 runtime = backend.cpu_runtime()
@@ -306,23 +306,46 @@ def from_onnx(model: ModelProto) -> backend.GraphHandler:
 
 
 def to_onnx(graph: backend.GraphHandler):
+    class Context:
+        names: Dict[Any, str] = dict()  # 记录所有对象的名字，包括张量和算子
+        nodes: List[NodeProto] = []  # 保存所有算子
+        count_op: Dict[backend.OpType, int] = dict()  # 统计每个算子出现次数，用于命名
+        count_in = 0  # 统计输入张量数量，用于命名
+        count_out = 0  # 统计输出张量数量，用于命名
+
+        def name_op(self, op: backend.Operator) -> Tuple[backend.OpType, str]:
+            ty = op.op_type()
+            name = "{}{}".format(ty.name, self.count_op.setdefault(ty, 0) + 1)
+            self.names[op] = name
+            self.count_op[ty] += 1
+            return ty, name
+
+        def push_output(self, name: str, tensor: backend.Tensor) -> None:
+            self.names[tensor] = name
+
+        def push_input(self, tensor: backend.Tensor) -> str:
+            name = self.names.get(tensor)
+            if name is None:
+                self.count_in += 1
+                name = "input{}".format(self.count_in)
+                self.names[tensor] = name
+            return name
+
+        def push_node(self, node: NodeProto) -> None:
+            self.nodes.append(node)
+
+    # 拓扑排序
     if not graph.topo_sort():
         raise Exception("Sorting fails")
 
-    ops = graph.operators()
+    ops = graph.operators()  # 图中所有算子（节点）
 
-    names: Dict[Any, str] = dict()
-    nodes: List[NodeProto] = []
-    count_op: Dict[backend.OpType, int] = dict()
-    count_in = 0
+    context = Context()
 
     for op in ops:
-        ty = op.op_type()
-        name = "{}{}".format(ty.name, count_op.setdefault(ty, 0) + 1)
+        ty, name = context.name_op(op)
         inputs = op.inputs()
         outputs = op.outputs()
-        names[op] = name
-        count_op[ty] += 1
         if ty == backend.OpType.Matmul:
             raise Exception("TODO")
         elif ty == backend.OpType.BatchNorm:
@@ -331,71 +354,17 @@ def to_onnx(graph: backend.GraphHandler):
             raise Exception("TODO")
         elif ty == backend.OpType.AvgPool:
             raise Exception("TODO")
-        elif ty == backend.OpType.Add:
-            names[outputs[0]] = name
-            if inputs[0] in names:
-                a = names[inputs[0]]
-            else:
-                count_in += 1
-                a = "input{}".format(count_in)
-            if inputs[1] in names:
-                b = names[inputs[1]]
-            else:
-                count_in += 1
-                b = "input{}".format(count_in)
-            nodes.append(make_node("Add", [a, b], [name], name))
-        elif ty == backend.OpType.Sub:
-            names[outputs[0]] = name
-            if inputs[0] in names:
-                a = names[inputs[0]]
-            else:
-                count_in += 1
-                a = "input{}".format(count_in)
-            if inputs[1] in names:
-                b = names[inputs[1]]
-            else:
-                count_in += 1
-                b = "input{}".format(count_in)
-            nodes.append(make_node("Sub", [a, b], [name], name))
-        elif ty == backend.OpType.Mul:
-            names[outputs[0]] = name
-            if inputs[0] in names:
-                a = names[inputs[0]]
-            else:
-                count_in += 1
-                a = "input{}".format(count_in)
-            if inputs[1] in names:
-                b = names[inputs[1]]
-            else:
-                count_in += 1
-                b = "input{}".format(count_in)
-            nodes.append(make_node("Mul", [a, b], [name], name))
-        elif ty == backend.OpType.Div:
-            names[outputs[0]] = name
-            if inputs[0] in names:
-                a = names[inputs[0]]
-            else:
-                count_in += 1
-                a = "input{}".format(count_in)
-            if inputs[1] in names:
-                b = names[inputs[1]]
-            else:
-                count_in += 1
-                b = "input{}".format(count_in)
-            nodes.append(make_node("Div", [a, b], [name], name))
-        elif ty == backend.OpType.Pow:
-            names[outputs[0]] = name
-            if inputs[0] in names:
-                a = names[inputs[0]]
-            else:
-                count_in += 1
-                a = "input{}".format(count_in)
-            if inputs[1] in names:
-                b = names[inputs[1]]
-            else:
-                count_in += 1
-                b = "input{}".format(count_in)
-            nodes.append(make_node("Pow", [a, b], [name], name))
+        elif ty in [
+            backend.OpType.Add,
+            backend.OpType.Sub,
+            backend.OpType.Mul,
+            backend.OpType.Div,
+            backend.OpType.Pow,
+        ]:
+            context.push_output(name, outputs[0])
+            a = context.push_input(inputs[0])
+            b = context.push_input(inputs[1])
+            context.push_node(make_node(ty.name, [a, b], [name], name))
         elif ty == backend.OpType.Relu:
             raise Exception("TODO")
         elif ty == backend.OpType.Sigmoid:
@@ -425,7 +394,7 @@ def to_onnx(graph: backend.GraphHandler):
         else:
             raise Exception("Unsupported OpType {}".format(ty.name))
 
-    print(names)
+    print(context.names)
 
 
 def parse_onnx(model: ModelProto):
diff --git a/src/ffi/ffi_infinitensor.cc b/src/ffi/ffi_infinitensor.cc
index ceb641d7..45293576 100644
--- a/src/ffi/ffi_infinitensor.cc
+++ b/src/ffi/ffi_infinitensor.cc
@@ -77,7 +77,7 @@ void init_graph_builder(py::module &m) {
     py::class_<RuntimeObj, std::shared_ptr<RuntimeObj>>(m, "Runtime");
     py::class_<CpuRuntimeObj, std::shared_ptr<CpuRuntimeObj>, RuntimeObj>(
         m, "CpuRuntime");
-    py::class_<TensorObj, std::shared_ptr<TensorObj>>(m, "TensorObj")
+    py::class_<TensorObj, std::shared_ptr<TensorObj>>(m, "Tensor")
         .def("src", &TensorObj::getOutputOf, policy::move);
     py::class_<OperatorObj, std::shared_ptr<OperatorObj>>(m, "Operator")
         .def("op_type", &OperatorObj::getOpType, policy::automatic)