diff --git a/example/mnist/custom_fx2trt.py b/example/mnist/custom_fx2trt.py
new file mode 100644
index 0000000..973e0c0
--- /dev/null
+++ b/example/mnist/custom_fx2trt.py
@@ -0,0 +1,223 @@
+# Copyright 2021 Yan Yan
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+
+"""
+This example shows how to write custom fx2trt like tool to convert
+pytorch model to tensorrt.
+"""
+
+from __future__ import print_function
+
+import argparse
+import contextlib
+import copy
+from typing import Dict, Optional
+
+import torch
+import torch.ao.quantization
+import torch.ao.quantization.quantize_fx as qfx
+import torch.cuda.amp
+import torch.fx
+import torch.nn as nn
+import torch.optim as optim
+
+from torch.fx import Tracer
+import tensorrt as trt 
+
+from spconv.pytorch.quantization.interpreter import NetworkInterpreter, register_node_handler, register_method_handler
+from spconv.pytorch.cppcore import torch_tensor_to_tv
+import numpy as np 
+import spconv.constants as spconvc
+import torch.nn.functional as F
+
+def _simple_repr(x):
+    return f"Tensor[{x.shape}|{x.dtype}]"
+# add verbose for ITensor
+trt.ITensor.__repr__ = _simple_repr
+
+class NetDense(nn.Module):
+    def __init__(self):
+        super(NetDense, self).__init__()
+        self.conv1 = nn.Conv2d(1, 32, 3, 1)
+        self.conv2 = nn.Conv2d(32, 64, 3, 1)
+        self.dropout1 = nn.Dropout(0.25)
+        self.dropout2 = nn.Dropout(0.5)
+        self.fc1 = nn.Linear(9216, 128)
+        self.fc2 = nn.Linear(128, 10)
+        self.conv_pool = nn.Conv2d(64, 64, 2, 2)
+
+    def forward(self, x):
+        x = self.conv1(x)
+        x = F.relu(x)
+        x = self.conv2(x)
+        x = F.relu(x)
+        x = self.conv_pool(x, 2)
+        x = self.dropout1(x)
+        x = torch.flatten(x, 1)
+        x = self.fc1(x)
+        x = F.relu(x)
+        x = self.dropout2(x)
+        x = self.fc2(x)
+        if self.training:
+            x = F.log_softmax(x, dim=1)
+        return x
+
+def _activation(net, x, act_type, alpha=None, beta=None, name=None):
+    layer = net.add_activation(x, act_type)
+    if alpha is not None:
+        layer.alpha = alpha
+    if beta is not None:
+        layer.beta = beta
+    output = layer.get_output(0)
+    if name is not None:
+        output.name = name
+        layer.name = name
+    return output
+
+def _trt_reshape(net, inp, shape, name):
+    layer = net.add_shuffle(inp)
+    layer.reshape_dims = shape
+    output = layer.get_output(0)
+    layer.name = name
+    output.name = name
+    return output
+
+# add module handler
+@register_node_handler(nn.Conv2d)
+def _conv2d(net, target: nn.Conv2d, args, kwargs, name: str):
+    x = args[0]
+    bias = target.bias
+    if target.bias is None:
+        bias = None 
+    else:
+        bias = target.bias.detach().cpu().numpy()
+    weight = target.weight.detach().cpu().numpy()
+    
+    O, I_groups, *ksize = weight.shape
+    I = I_groups * target.groups
+    stride = target.stride
+    padding = target.padding
+    dilation = target.dilation
+    weight_qdq = None
+    if not isinstance(weight, np.ndarray):
+        weight_qdq = weight
+        weight = trt.Weights()
+    else:
+        weight = trt.Weights(weight)
+    if bias is None:
+        bias = trt.Weights()
+    else:
+        bias = trt.Weights(bias)
+    layer = net.add_convolution_nd(x, O, tuple(ksize), weight, bias)
+    if weight_qdq is not None:
+        # in explicit quantization, we need this
+        layer.set_input(1, weight_qdq)
+    layer.stride_nd = tuple(stride)
+    layer.padding_nd = tuple(padding)
+    layer.dilation_nd = tuple(dilation)
+    layer.num_groups = target.groups
+    output = layer.get_output(0)
+    output.name = name
+    layer.name = name
+    return output
+    
+@register_node_handler(F.relu)
+def _relu(net, target: nn.Conv2d, args, kwargs, name: str):
+    return _activation(net, args[0], trt.ActivationType.RELU, name=name)
+
+
+@register_node_handler(nn.Dropout)
+@register_node_handler(nn.Dropout1d)
+@register_node_handler(nn.Dropout2d)
+@register_node_handler(nn.Dropout3d)
+def _identity_single(net, target, args, kwargs, name: str):
+    return args[0]
+
+@register_node_handler(torch.flatten)
+def _flatten(net, target, args, kwargs, name: str):
+    start_dim = args[1]
+    x = args[0]
+    return _trt_reshape(net, x, [*x.shape[:start_dim], int(np.prod(x.shape[start_dim:]))], name)
+
+def _dot(net, x, y, transpose_x=False, transpose_y=False, name=None):
+    mode_x = trt.MatrixOperation.NONE
+    if transpose_x:
+        mode_x = trt.MatrixOperation.TRANSPOSE
+    mode_y = trt.MatrixOperation.NONE
+    if transpose_y:
+        mode_y = trt.MatrixOperation.TRANSPOSE
+    layer = net.add_matrix_multiply(x, mode_x, y, mode_y)
+
+    output = layer.get_output(0)
+    assert name is not None
+
+    output.name = name
+    layer.name = name
+    return output
+
+def _constant(net, array, name):
+    array = np.array(array)
+    layer = net.add_constant(array.shape, trt.Weights(array.reshape(-1)))
+    out = layer.get_output(0)
+    layer.name = name
+    out.name = name
+    return out
+
+@register_node_handler(nn.Linear)
+def _linear(net, target: nn.Linear, args, kwargs, name: str):
+    x = args[0]
+    bias = target.bias
+    if target.bias is None:
+        bias = None 
+    else:
+        bias = target.bias.detach().cpu().numpy()
+    weight = target.weight.detach().cpu().numpy()
+    weight_trt = _constant(net, weight, name + "/weight")
+    res = _dot(net, x, weight_trt, transpose_y=True, name=name)
+    if bias is not None:
+        bias_trt = _constant(net, bias.reshape(1, -1), name + "/bias")
+        layer = net.add_elementwise(res, bias_trt, trt.ElementWiseOperation.SUM)
+        res = layer.get_output(0)
+        add_name = name + "/add"
+        res.name = add_name
+        layer.name = add_name
+    return res 
+
+def main():
+    model = NetDense()
+    model = model.eval()
+    tc = Tracer()
+    graph_trace = tc.trace(model)
+    gm = torch.fx.GraphModule(tc.root, graph_trace)
+    import tensorrt as trt 
+    TRT_LOGGER = trt.Logger(trt.Logger.WARNING)
+    # try:
+    #     import pycuda.autoprimaryctx
+    # except ModuleNotFoundError:
+    #     import pycuda.autoinit
+    with trt.Runtime(TRT_LOGGER) as rt:
+        with trt.Builder(TRT_LOGGER) as builder:
+            with builder.create_network(True) as network:
+                config = builder.create_builder_config()
+                config.max_workspace_size = 1 << 30
+                input_tensor = network.add_input(name="inp", dtype=trt.float32, shape=[1, 1, 28, 28])
+                interp = NetworkInterpreter(network, gm, [input_tensor], verbose=True)
+                # get converted outputs from interp
+                outputs = interp.run()
+                network.mark_output(tensor=outputs[0])
+                plan = builder.build_serialized_network(network, config)
+                engine = rt.deserialize_cuda_engine(plan)
+
+if __name__ == '__main__':
+    main()
diff --git a/spconv/pytorch/interpreter.py b/spconv/pytorch/interpreter.py
new file mode 100644
index 0000000..c5c422e
--- /dev/null
+++ b/spconv/pytorch/interpreter.py
@@ -0,0 +1,129 @@
+from typing import Any, Dict, List, Optional, Set, Type
+
+import torch
+import torch.fx
+
+REGISTERED_NODE_HANDLERS: Dict[Any, Any] = {}
+
+
+def register_node_handler(*names):
+
+    def wrap_func(handler):
+        global REGISTERED_NODE_HANDLERS
+        for n in names:
+            REGISTERED_NODE_HANDLERS[n] = handler
+
+        def new_handler(*args, **kwargs):
+            return handler(*args, **kwargs)
+
+        return new_handler
+
+    return wrap_func
+
+
+def register_method_handler(name: str, tensor_classes):
+    if not isinstance(tensor_classes, (list, tuple)):
+        tensor_classes = [tensor_classes]
+
+    def wrap_func(handler):
+        global REGISTERED_NODE_HANDLERS
+        for tcls in tensor_classes:
+            REGISTERED_NODE_HANDLERS[(tcls, name)] = handler
+
+        def new_handler(*args, **kwargs):
+            return handler(*args, **kwargs)
+
+        return new_handler
+
+    return wrap_func
+
+
+def get_node_handler(name):
+    global REGISTERED_NODE_HANDLERS
+    msg = "missing handler " + str(name)
+    msg += ", available handlers: {}".format(
+        list(REGISTERED_NODE_HANDLERS.keys()))
+    assert name in REGISTERED_NODE_HANDLERS, msg
+    return REGISTERED_NODE_HANDLERS[name]
+
+
+class NetworkInterpreter(torch.fx.Interpreter):
+
+    def __init__(self,
+                 network_ctx,
+                 module: torch.fx.GraphModule,
+                 inputs: List[Any],
+                 verbose: bool = False):
+        super().__init__(module)
+        self.network_ctx = network_ctx
+        self._inputs = inputs
+        self._outputs = None
+        self._cur_node_name: Optional[str] = None
+        self._input_names: List[str] = []
+        self._output_names: List[str] = []
+        self._verbose = verbose
+
+    def run(self):
+        super().run(*self._inputs)
+        assert self._outputs is not None
+        return self._outputs
+
+    def run_node(self, n):
+        self._cur_node_name = str(n)
+        return super().run_node(n)
+
+    def call_module(self, target, args, kwargs):
+        assert isinstance(target, str)
+        submod = self.fetch_attr(target)
+        submod_type = getattr(submod, "_base_class_origin", type(submod))
+        type_str = submod_type.__qualname__
+        type_str_parts = type_str.split(".")
+        msg = f"[Module.{type_str_parts[-1]}]{target}({args}|{kwargs}) => "
+
+        try:
+            converter = get_node_handler(submod_type)
+            res = converter(self.network_ctx, submod, args, kwargs,
+                            self._cur_node_name)
+            msg += f"{res}"
+            if self._verbose:
+                print(msg)
+            return res
+        except Exception as e:
+            if self._verbose:
+                print(msg)
+            raise e
+
+    def call_function(self, target, args, kwargs):
+        msg = f"[Func]{target}({args}|{kwargs}) => "
+        try:
+            converter = get_node_handler(target)
+            res = converter(self.network_ctx, target, args, kwargs,
+                            self._cur_node_name)
+            msg += f"{res}"
+            if self._verbose:
+                print(msg)
+            return res
+        except Exception as e:
+            if self._verbose:
+                print(msg)
+            raise e
+
+    def call_method(self, target, args, kwargs):
+        msg = f"[Method]{target}({args}|{kwargs}) => "
+        assert isinstance(target, str)
+        try:
+            key = (type(args[0]), target)
+            converter = get_node_handler(key)
+            res = converter(self.network_ctx, target, args, kwargs,
+                            self._cur_node_name)
+            msg += f"{res}"
+            if self._verbose:
+                print(msg)
+            return res
+        except Exception as e:
+            if self._verbose:
+                print(msg)
+            raise e
+
+    def output(self, target, args, kwargs):
+        self._outputs = args
diff --git a/spconv/pytorch/quantization/interpreter.py b/spconv/pytorch/quantization/interpreter.py
index b6677a4..060d5ce 100644
--- a/spconv/pytorch/quantization/interpreter.py
+++ b/spconv/pytorch/quantization/interpreter.py
@@ -1,129 +1 @@
-from typing import Any, Dict, List, Optional, Set, Type
-
-import torch
-import torch.fx
-
-REGISTERED_NODE_HANDLERS: Dict[Any, Any] = {}
-
-
-def register_node_handler(*names):
-
-    def wrap_func(handler):
-        global REGISTERED_NODE_HANDLERS
-        for n in names:
-            REGISTERED_NODE_HANDLERS[n] = handler
-
-        def new_handler(inputs, attributes, scope):
-            return handler(inputs, attributes, scope)
-
-        return new_handler
-
-    return wrap_func
-
-
-def register_method_handler(name: str, tensor_classes):
-    if not isinstance(tensor_classes, (list, tuple)):
-        tensor_classes = [tensor_classes]
-
-    def wrap_func(handler):
-        global REGISTERED_NODE_HANDLERS
-        for tcls in tensor_classes:
-            REGISTERED_NODE_HANDLERS[(tcls, name)] = handler
-
-        def new_handler(inputs, attributes, scope):
-            return handler(inputs, attributes, scope)
-
-        return new_handler
-
-    return wrap_func
-
-
-def get_node_handler(name):
-    global REGISTERED_NODE_HANDLERS
-    msg = "missing handler " + str(name)
-    msg += ", available handlers: {}".format(
-        list(REGISTERED_NODE_HANDLERS.keys()))
-    assert name in REGISTERED_NODE_HANDLERS, msg
-    return REGISTERED_NODE_HANDLERS[name]
-
-
-class NetworkInterpreter(torch.fx.Interpreter):
-
-    def __init__(self,
-                 network_ctx,
-                 module: torch.fx.GraphModule,
-                 inputs: List[Any],
-                 verbose: bool = False):
-        super().__init__(module)
-        self.network_ctx = network_ctx
-        self._inputs = inputs
-        self._outputs = None
-        self._cur_node_name: Optional[str] = None
-        self._input_names: List[str] = []
-        self._output_names: List[str] = []
-        self._verbose = verbose
-
-    def run(self):
-        super().run(*self._inputs)
-        assert self._outputs is not None
-        return self._outputs
-
-    def run_node(self, n):
-        self._cur_node_name = str(n)
-        return super().run_node(n)
-
-    def call_module(self, target, args, kwargs):
-        assert isinstance(target, str)
-        submod = self.fetch_attr(target)
-        submod_type = getattr(submod, "_base_class_origin", type(submod))
-        type_str = submod_type.__qualname__
-        type_str_parts = type_str.split(".")
-        msg = f"[Module.{type_str_parts[-1]}]{target}({args}|{kwargs}) => "
-
-        try:
-            converter = get_node_handler(submod_type)
-            res = converter(self.network_ctx, submod, args, kwargs,
-                            self._cur_node_name)
-            msg += f"{res}"
-            if self._verbose:
-                print(msg)
-            return res
-        except Exception as e:
-            if self._verbose:
-                print(msg)
-            raise e
-
-    def call_function(self, target, args, kwargs):
-        msg = f"[Func]{target}({args}|{kwargs}) => "
-        try:
-            converter = get_node_handler(target)
-            res = converter(self.network_ctx, target, args, kwargs,
-                            self._cur_node_name)
-            msg += f"{res}"
-            if self._verbose:
-                print(msg)
-            return res
-        except Exception as e:
-            if self._verbose:
-                print(msg)
-            raise e
-
-    def call_method(self, target, args, kwargs):
-        msg = f"[Method]{target}({args}|{kwargs}) => "
-        assert isinstance(target, str)
-        try:
-            key = (type(args[0]), target)
-            converter = get_node_handler(key)
-            res = converter(self.network_ctx, target, args, kwargs,
-                            self._cur_node_name)
-            msg += f"{res}"
-            if self._verbose:
-                print(msg)
-            return res
-        except Exception as e:
-            if self._verbose:
-                print(msg)
-            raise e
-
-    def output(self, target, args, kwargs):
-        self._outputs = args
+from ..interpreter import *
\ No newline at end of file