diff --git a/imperative/python/megengine/traced_module/_passes/matcher.py b/imperative/python/megengine/traced_module/_passes/matcher.py
new file mode 100644
index 00000000..db4765ef
--- /dev/null
+++ b/imperative/python/megengine/traced_module/_passes/matcher.py
@@ -0,0 +1,183 @@
+# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+#
+# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+from collections import OrderedDict, defaultdict
+from functools import partial
+
+from ...logger import get_logger
+from ..expr import (
+    Expr,
+    is_apply_def,
+    is_call_function,
+    is_call_module,
+    is_call_tensor_method,
+    is_constant,
+)
+from .pattern import (
+    AnyPattern,
+    ApplyDefPattern,
+    CallPattern,
+    ConstantPattern,
+    ExprPattern,
+    FunctionPattern,
+    ModulePattern,
+    OrPattern,
+    TensorMethodPattern,
+    VarPattern,
+)
+from .utils import register_obj
+
+logger = get_logger(__name__)
+
+
+class PatternMatcher:
+
+    method_dict = {}
+    register_visiter_func = partial(register_obj, _dict=method_dict)
+
+    def __init__(self) -> None:
+        self.matched_patterns = []
+        self.matched_exprs = OrderedDict()
+
+    def match(self, pattern: ExprPattern, expr: Expr) -> bool:
+        self.matched_exprs.clear()
+        self.matched_patterns.clear()
+        pattern.check_users(False)
+        res = self.visit_pattern(pattern, expr)
+        if res and not self._check_users():
+            self.clear_map(0)
+            res = False
+        self._clear_pattern_users()
+        return res
+
+    def clear_map(self, mark):
+        for _ in range(len(self.matched_patterns) - mark):
+            p = self.matched_patterns.pop()
+            self.matched_exprs.pop(p)
+            p._clear_users()
+
+    def _clear_pattern_users(self):
+        for p in self.matched_patterns:
+            p._clear_users()
+
+    def _check_users(self) -> bool:
+        for pat, expr in self.matched_exprs.items():
+            if pat._check_users:
+                pattern_users = pat._users
+                if len(expr.outputs) != 1:
+                    logger.warning(
+                        "only support single output, and the matching "
+                        "result may be wrong"
+                    )
+                    continue
+                expr_users = expr.outputs[0].users
+                if len(pattern_users) != len(expr_users):
+                    return False
+                for pat, expr in zip(pattern_users, expr_users):
+                    if self.matched_exprs[pat] != expr:
+                        return False
+        return True
+
+    def visit_pattern(self, pattern: ExprPattern, expr: Expr) -> bool:
+        if pattern in self.matched_exprs:
+            if self.matched_exprs[pattern] is expr:
+                if isinstance(pattern, (OrPattern)):
+                    assert self._visit_or_pattern(pattern, expr) == True
+                return True
+            else:
+                return False
+        else:
+            mark = len(self.matched_patterns)
+            visiter = self.method_dict.get(type(pattern))
+            matched = visiter(self, pattern, expr)
+            if matched:
+                self.matched_patterns.append(pattern)
+                self.matched_exprs[pattern] = expr
+            else:
+                self.clear_map(mark)
+            return matched
+
+    @register_visiter_func(OrPattern)
+    def _visit_or_pattern(self, pattern: OrPattern, expr: Expr) -> bool:
+        if self.visit_pattern(pattern.left, expr):
+            if pattern._users:
+                pattern.left._add_users(pattern._users[-1])
+            return True
+        if self.visit_pattern(pattern.right, expr):
+            if pattern._users:
+                pattern.right._add_users(pattern._users[-1])
+            return True
+        return False
+
+    @register_visiter_func(CallPattern)
+    def _visit_call_pattern(self, pattern: CallPattern, expr: Expr) -> bool:
+        mark = len(self.matched_patterns)
+        match_res = self.visit_pattern(pattern.op, expr)
+        if not match_res:
+            self.clear_map(mark)
+            return False
+        inputs = expr.inputs
+        if isinstance(pattern.op, ModulePattern):
+            inputs = inputs[1:]
+        if (pattern._match_all_args and len(pattern.args) != len(inputs)) or (
+            not pattern._match_all_args and len(pattern.args) > len(inputs)
+        ):
+            self.clear_map(mark)
+            return False
+        for i, pat in enumerate(pattern.args):
+            pat._add_users(pattern)
+            match_res = self.visit_pattern(pat, inputs[i].expr)
+            if not match_res:
+                pat._clear_users()
+                self.clear_map(mark)
+                return False
+        return True
+
+    @register_visiter_func(ModulePattern)
+    def _visit_module_pattern(self, pattern: ModulePattern, expr: Expr) -> bool:
+        if not is_call_module(expr, pattern.target):
+            return False
+        module = expr.inputs[0].owner
+        for key, target in pattern.attrs.items():
+            value = getattr(module, key, None)
+            if target != value:
+                return False
+        return True
+
+    @register_visiter_func(FunctionPattern)
+    def _visit_function_pattern(self, pattern: FunctionPattern, expr: Expr) -> bool:
+        if not is_call_function(expr, pattern.target):
+            return False
+        kwargs = expr.kwargs
+        for key, target in pattern.params.items():
+            value = kwargs.get(key, None)
+            if target != value:
+                return False
+        return True
+
+    @register_visiter_func(TensorMethodPattern)
+    def _visit_tensor_method_pattern(
+        self, pattern: TensorMethodPattern, expr: Expr
+    ) -> bool:
+        return is_call_tensor_method(expr, pattern.target)
+
+    @register_visiter_func(ApplyDefPattern)
+    def _visit_apply_pattern(self, pattern: ApplyDefPattern, expr: Expr) -> bool:
+        return is_apply_def(expr, pattern.target)
+
+    @register_visiter_func(ConstantPattern)
+    def _visit_const_pattern(self, pattern: ConstantPattern, expr: Expr) -> bool:
+        return is_constant(expr)
+
+    @register_visiter_func(VarPattern)
+    def _visit_var_pattern(self, pattern: VarPattern, expr: Expr) -> bool:
+        return not is_constant(expr)
+
+    @register_visiter_func(AnyPattern)
+    def _visit_any_pattern(self, pattern: AnyPattern, expr: Expr) -> bool:
+        return True
diff --git a/imperative/python/megengine/traced_module/_passes/pattern.py b/imperative/python/megengine/traced_module/_passes/pattern.py
new file mode 100644
index 00000000..1f559f4b
--- /dev/null
+++ b/imperative/python/megengine/traced_module/_passes/pattern.py
@@ -0,0 +1,252 @@
+# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+#
+# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+from abc import abstractmethod
+from typing import Any, Callable, Dict, List
+
+from ...core._imperative_rt import OpDef
+from ...logger import get_logger
+from ...module import Module
+from ..expr import Expr
+from ..node import Node
+
+logger = get_logger(__name__)
+
+
+class ExprPattern:
+    def __init__(self):
+        self._check_users = True
+        self._users = []
+
+    def __call__(self, *args):
+        args = list(args)
+        if len(args) == 1 and args[0] is None:
+            args = None
+        return CallPattern(self, *args)
+
+    def __add__(self, other):
+        return is_op("__add__")(self, other)
+
+    def __iadd__(self, other):
+        return is_op("__iadd__")(self, other)
+
+    def __radd__(self, other):
+        return is_op("__radd__")(self, other)
+
+    def __sub__(self, other):
+        return is_op("__sub__")(self, other)
+
+    def __isub__(self, other):
+        return is_op("__isub__")(self, other)
+
+    def __rsub__(self, other):
+        return is_op("__rsub__")(self, other)
+
+    def __mul__(self, other):
+        return is_op("__mul__")(self, other)
+
+    def __imul__(self, other):
+        return is_op("__imul__")(self, other)
+
+    def __rmul__(self, other):
+        return is_op("__rmul__")(self, other)
+
+    def __truediv__(self, other):
+        return is_op("__truediv__")(self, other)
+
+    def __itruediv__(self, other):
+        return is_op("__itruediv__")(self, other)
+
+    def __rtruediv__(self, other):
+        return is_op("__rtruediv__")(self, other)
+
+    def __or__(self, other):
+        assert isinstance(other, ExprPattern)
+        return OrPattern(self, other)
+
+    def get_output(self, index):
+        raise NotImplementedError
+
+    def check_users(self, check: bool = True):
+        self._check_users = check
+        return self
+
+    def _add_users(self, pattern: "ExprPattern"):
+        self._users.append(pattern)
+
+    def _clear_users(self,):
+        self._users.clear()
+
+    def __getitem__(self, index):
+        return is_op("__getitem__")(self, index)
+
+    def has_attr(self, **attrs):
+        logger.warning("has_param only support ModulePattern")
+        return self
+
+    def has_param(self, **params):
+        logger.warning("has_param only support FunctionPattern")
+        return self
+
+    @abstractmethod
+    def __repr__(self) -> str:
+        raise NotImplementedError
+
+
+class CallPattern(ExprPattern):
+    def __init__(self, op: ExprPattern, *args: List[ExprPattern]):
+        super().__init__()
+        self.op = op
+        self.args = list(filter(lambda x: isinstance(x, ExprPattern), args))
+        self._match_all_args = True
+
+    def __repr__(self) -> str:
+        return "{}({})".format(self.op, ",".join(str(x) for x in self.args))
+
+    def not_all_args(self):
+        self._match_all_args = False
+
+    def check_users(self, check: bool = True):
+        self._check_users = check
+        self.op.check_users(check)
+        return self
+
+    def _add_users(self, pattern: "ExprPattern"):
+        self._users.append(pattern)
+        self.op._add_users(pattern)
+
+    def _clear_users(self):
+        self._users.clear()
+        self.op._clear_users()
+
+
+class OrPattern(ExprPattern):
+    def __init__(self, left: ExprPattern, right: ExprPattern):
+        super().__init__()
+        self.left = left
+        self.right = right
+
+    def __repr__(self) -> str:
+        return "({}|{})".format(self.left, self.right)
+
+    def check_users(self, check: bool = True):
+        self._check_users = check
+        self.left.check_users(check)
+        self.right.check_users(check)
+        return self
+
+    def _clear_users(self):
+        self._users.clear()
+        self.left._clear_users()
+        self.right._clear_users()
+
+
+class GetOutputPaterrn(ExprPattern):
+    def __init__(self, op, index):
+        super().__init__()
+        self.op = op
+        self.index = index
+
+    def __repr__(self) -> str:
+        return "{}[{}]".format(self.op, self.index)
+
+
+class ModulePattern(ExprPattern):
+    def __init__(self, module_cls: Module) -> None:
+        super().__init__()
+        self.attrs = {}
+        self.target = module_cls
+
+    def has_attr(self, **attrs):
+        self.attrs.update(attrs)
+        return self
+
+    def __repr__(self) -> str:
+        return "{}".format(self.target.__name__)
+
+
+class FunctionPattern(ExprPattern):
+    def __init__(self, func: Callable):
+        super().__init__()
+        self.params = {}
+        self.target = func
+
+    def has_params(self, **params):
+        self.params.update(params)
+        return self
+
+    def __repr__(self) -> str:
+        return "{}".format(self.target.__name__)
+
+
+class TensorMethodPattern(ExprPattern):
+    def __init__(self, method: str):
+        super().__init__()
+        self.target = method
+
+    def __repr__(self) -> str:
+        return self.target
+
+
+class ApplyDefPattern(ExprPattern):
+    def __init__(self, opdef: OpDef):
+        super().__init__()
+        self.target = opdef
+
+    def __repr__(self) -> str:
+        return "{}".format(self.target.__name__)
+
+
+class VarPattern(ExprPattern):
+    def __init__(self):
+        super().__init__()
+
+    def __repr__(self) -> str:
+        return "var"
+
+
+class ConstantPattern(ExprPattern):
+    def __init__(self):
+        super().__init__()
+
+    def __repr__(self) -> str:
+        return "const"
+
+
+class AnyPattern(ExprPattern):
+    def __init__(self):
+        super().__init__()
+
+    def __repr__(self) -> str:
+        return "any"
+
+
+def is_op(target):
+    if isinstance(target, type):
+        if issubclass(target, Module):
+            return ModulePattern(target)
+        if issubclass(target, OpDef):
+            return ApplyDefPattern(target)
+    elif callable(target):
+        return FunctionPattern(target)
+    elif isinstance(target, str):
+        return TensorMethodPattern(target)
+    else:
+        raise ValueError("not support")
+
+
+def is_const():
+    return ConstantPattern().check_users(False)
+
+
+def any_node():
+    return AnyPattern()
+
+
+def is_var():
+    return VarPattern()
diff --git a/imperative/python/megengine/traced_module/_passes/utils.py b/imperative/python/megengine/traced_module/_passes/utils.py
new file mode 100644
index 00000000..ed25072e
--- /dev/null
+++ b/imperative/python/megengine/traced_module/_passes/utils.py
@@ -0,0 +1,38 @@
+# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+#
+# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+import copy
+from typing import Any, Dict, List
+
+from ..expr import Expr, is_constant, is_getattr
+from ..node import Node, TensorNode
+
+
+def register_obj(objs: List[Any], _dict: Dict):
+    if not isinstance(objs, List):
+        objs = [objs]
+
+    def _register(any_obj: Any):
+        for obj in objs:
+            _dict[obj] = any_obj
+        return any_obj
+
+    return _register
+
+
+def get_const_value(expr: Expr, fall_back: Any = None):
+    value = fall_back
+    if isinstance(expr, Node):
+        expr = expr.expr
+    if is_getattr(expr) and isinstance(expr.outputs[0], TensorNode):
+        module = expr.inputs[0].owner
+        assert module is not None
+        value = copy.deepcopy(expr.interpret(module)[0])
+    elif is_constant(expr):
+        value = copy.deepcopy(expr.interpret()[0])
+    return value