diff --git a/imperative/python/megengine/core/ops/builtin/__init__.py b/imperative/python/megengine/core/ops/builtin/__init__.py
index 2029f277f082571a590419a5ff8661045a34543b..13598687effbd6f542e2c7cc86951174b9675458 100644
--- a/imperative/python/megengine/core/ops/builtin/__init__.py
+++ b/imperative/python/megengine/core/ops/builtin/__init__.py
@@ -6,9 +6,6 @@
 # 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 warnings
-from typing import Union
-
 from ..._imperative_rt import OpDef, ops
 
 __all__ = ["OpDef"]
diff --git a/imperative/python/megengine/core/tensor/dtype.py b/imperative/python/megengine/core/tensor/dtype.py
index ccbdd90163748c86e4011f5546a87cc18a47280b..f68fde1215674aac35af500573ee2b258f62b508 100644
--- a/imperative/python/megengine/core/tensor/dtype.py
+++ b/imperative/python/megengine/core/tensor/dtype.py
@@ -5,22 +5,24 @@
 # 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 collections
+from collections import namedtuple
 from typing import Union
 
 import numpy as np
 
-# normal dtype related
-from .._imperative_rt import bfloat16, intb1, intb2, intb4
 from .._imperative_rt.common import (
+    bfloat16,
     get_scale,
     get_zero_point,
+    intb1,
+    intb2,
+    intb4,
     is_dtype_equal,
     is_quantize,
 )
 
 
+# normal dtype related
 def is_lowbit(dtype):
     return (dtype is intb1) or (dtype is intb2) or (dtype is intb4)
 
@@ -30,34 +32,80 @@ def is_bfloat16(dtype):
 
 
 # quantization dtype related
-_QuantDtypeMetadata = collections.namedtuple(
-    "QuantDtypeMetadata", ["name", "np_dtype_str", "is_unsigned", "qmin", "qmax",]
-)
 
-_metadata_dict = {
-    "quint8": _QuantDtypeMetadata("Quantized8Asymm", "uint8", True, 0, 255),
-    "qint8": _QuantDtypeMetadata("QuantizedS8", "int8", False, -128, 127),
-    "quint4": _QuantDtypeMetadata("Quantized4Asymm", "uint8", True, 0, 15),
-    "qint4": _QuantDtypeMetadata("QuantizedS4", "int8", False, -8, 7),
-    "qint32": _QuantDtypeMetadata(
-        "QuantizedS32", "int32", False, -(2 ** 31), 2 ** 31 - 1,
+# use namedtuple to make class immutable, comparable and easy to print
+class QuantDtypeMeta(
+    namedtuple(
+        "QuantDtypeMeta",
+        ["name", "cname", "np_dtype_str", "qmin", "qmax", "is_unsigned"],
+    )
+):
+    r"""
+    Store metadata for quantize dtype. Could be used to create custom quant dtype
+    for QAT when the network don't need to be converted for inference, but only
+    to export network metadata for third-party platform inference.
+
+    :param name: a unique name string.
+    :param cname: used in :func:`~.create_quantized_dtype` for model dump and inference.
+    :param np_dtype_str: used in :func:`~.create_quantized_dtype` to generate ``np.dtype``.
+    :param qmin: a int number indicating quant dtype's lowerbound.
+    :param qmax: a int number indicating quant dtype's upperbound.
+    :param is_unsigned: a helper value that could be inference from np_dtype_str.
+    """
+
+    def __new__(
+        cls,
+        name: str,
+        cname: str,
+        np_dtype_str: str,
+        qmin: int,
+        qmax: int,
+        is_unsigned: bool = None,
+    ):
+        assert isinstance(np_dtype_str, str)
+        is_unsigned = np_dtype_str[0] == "u" if is_unsigned is None else is_unsigned
+        return super().__new__(cls, name, cname, np_dtype_str, qmin, qmax, is_unsigned)
+
+    def __copy__(self):
+        return self
+
+    def __deepcopy__(self, _):
+        """
+        Ignore deepcopy so that a dtype meta can be treated as singleton, for more
+        strict check in :meth:`~.FakeQuantize.fake_quant_forward`.
+        """
+        return self
+
+
+_builtin_quant_dtypes = {
+    "quint8": QuantDtypeMeta("quint8", "Quantized8Asymm", "uint8", 0, 255),
+    "qint8": QuantDtypeMeta("qint8", "QuantizedS8", "int8", -128, 127),
+    "qint8_narrow": QuantDtypeMeta("qint8_narrow", "QuantizedS8", "int8", -127, 127),
+    "quint4": QuantDtypeMeta("quint4", "Quantized4Asymm", "uint8", 0, 15),
+    "qint4": QuantDtypeMeta("qint4", "QuantizedS4", "int8", -8, 7),
+    "qint32": QuantDtypeMeta(
+        "qint32", "QuantizedS32", "int32", -(2 ** 31), 2 ** 31 - 1,
     ),
     # NOTE: int2 is not supported for model dump yet
-    "quint2": _QuantDtypeMetadata(None, "uint8", True, 0, 3),
-    "qint2": _QuantDtypeMetadata(None, "int8", False, -2, 1),
+    "quint2": QuantDtypeMeta("quint2", None, "uint8", 0, 3),
+    "qint2": QuantDtypeMeta("qint2", None, "int8", -2, 1),
 }
 
 
-def _check_zero_point(zp: int, dtype_str: str):
-    qmin = _metadata_dict[dtype_str].qmin
-    qmax = _metadata_dict[dtype_str].qmax
+def _check_zero_point(zp: int, dtype_meta: QuantDtypeMeta):
+    qmin = dtype_meta.qmin
+    qmax = dtype_meta.qmax
     if zp < qmin or zp > qmax:
         raise ValueError(
-            "zero_point should be within [{}, {}] for {}".format(qmin, qmax, dtype_str)
+            "zero_point should be within [{}, {}] for {}".format(
+                qmin, qmax, dtype_meta.name
+            )
         )
 
 
-def get_quantized_dtype(dtype_str: str, scale: float, zp: Union[int, None]):
+def create_quantized_dtype(
+    dtype_meta: QuantDtypeMeta, scale: float, zp: Union[int, None]
+):
     r"""
     Get quantized dtype with metadata attribute according to _metadata_dict.
 
@@ -65,32 +113,34 @@ def get_quantized_dtype(dtype_str: str, scale: float, zp: Union[int, None]):
     not have ``zero_point``, to be consitent with tensor generated by calling
     compiled function from `CompGraph.compile(inputs, outspec)`.
 
-    :param dtype: a string indicating which dtype to return
+    :param dtype_meta: a QuantDtypeMeta indicating which dtype to return. the
+        ``cname`` attribute cannot be ``None``.
     :param scale: a number for scale to store in dtype's metadata
     :param zp: a number for zero_point to store in dtype's metadata
     """
-    metadata = _metadata_dict[dtype_str]
-    np_dtype_str = metadata.np_dtype_str
-    is_unsigned = metadata.is_unsigned
-    if is_unsigned:
+    if dtype_meta.cname is None:
+        raise ValueError("dtype {} without cname attr is not supported.")
+    if dtype_meta.is_unsigned:
         if zp is None or int(zp) != zp:
             raise ValueError("zero_point should be an integer")
         zp = int(zp)
-        _check_zero_point(zp, dtype_str)
+        _check_zero_point(zp, dtype_meta)
         return np.dtype(
-            np_dtype_str,
+            dtype_meta.np_dtype_str,
             metadata={
                 "mgb_dtype": {
-                    "name": metadata.name,
+                    "name": dtype_meta.cname,
                     "scale": float(scale),
                     "zero_point": zp,
                 }
             },
         )
     else:
+        # Don't trick to combine with is_unsigned. Metadata should not contain
+        # invalid field to keep consistent with c dtype.
         return np.dtype(
-            np_dtype_str,
-            metadata={"mgb_dtype": {"name": metadata.name, "scale": float(scale)}},
+            dtype_meta.np_dtype_str,
+            metadata={"mgb_dtype": {"name": dtype_meta.cname, "scale": float(scale)}},
         )
 
 
@@ -100,7 +150,7 @@ def quint8(scale, zero_point):
     ``zero_point`` (uint8). The real value represented by a quint8 data type is
     float_val = scale * (uint8_val - zero_point)
     """
-    return get_quantized_dtype("quint8", scale, zero_point)
+    return create_quantized_dtype(_builtin_quant_dtypes["quint8"], scale, zero_point)
 
 
 def qint8(scale):
@@ -108,7 +158,7 @@ def qint8(scale):
     Construct a quantized int8 data type with ``scale`` (float). The real value
     represented by a qint8 data type is float_val = scale * int8_val
     """
-    return get_quantized_dtype("qint8", scale, None)
+    return create_quantized_dtype(_builtin_quant_dtypes["qint8"], scale, None)
 
 
 def qint32(scale):
@@ -116,7 +166,7 @@ def qint32(scale):
     Construct a quantized int32 data type with ``scale`` (float). The real value
     represented by a qint32 data type is float_val = scale * int32_val
     """
-    return get_quantized_dtype("qint32", scale, None)
+    return create_quantized_dtype(_builtin_quant_dtypes["qint32"], scale, None)
 
 
 def quint4(scale, zero_point):
@@ -125,7 +175,7 @@ def quint4(scale, zero_point):
     ``zero_point`` (uint8). The real value represented by a quint4 data type is
     float_val = scale * (uint4_val - zero_point)
     """
-    return get_quantized_dtype("quint4", scale, zero_point)
+    return create_quantized_dtype(_builtin_quant_dtypes["quint4"], scale, zero_point)
 
 
 def qint4(scale):
@@ -133,42 +183,48 @@ def qint4(scale):
     Construct a quantized int4 data type with ``scale`` (float). The real value
     represented by a qint4 data type is float_val = scale * int4_val
     """
-    return get_quantized_dtype("qint4", scale, None)
+    return create_quantized_dtype(_builtin_quant_dtypes["qint4"], scale, None)
 
 
-def _convert_to_quantized_dtype(arr: np.ndarray, dtype: np.dtype, dtype_str: str):
-    metadata = _metadata_dict[dtype_str]
-    arr_metadata = dtype.metadata["mgb_dtype"]
+def _convert_to_quantized_dtype(
+    arr: np.ndarray, dtype: np.dtype, dtype_meta: QuantDtypeMeta
+):
     if not isinstance(arr, np.ndarray):
         raise ValueError("arr parameter should be instance of np.ndarray")
-    if not is_quantize(dtype) or arr_metadata["name"] != metadata.name:
-        raise ValueError("dtype parameter should be a {} dtype".format(dtype_str))
-    is_unsigned = metadata.is_unsigned
-    if is_unsigned:
+    if (
+        not is_quantize(dtype)
+        or dtype.metadata["mgb_dtype"]["name"] != dtype_meta.cname
+    ):
+        raise ValueError("dtype parameter should be a {} dtype".format(dtype_meta))
+    arr_metadata = dtype.metadata["mgb_dtype"]
+    if dtype_meta.is_unsigned:
         scale, zp = (
             arr_metadata["scale"],
             arr_metadata["zero_point"],
         )
         return (
             (np.round(arr / scale) + zp)
-            .clip(metadata.qmin, metadata.qmax)
+            .clip(dtype_meta.qmin, dtype_meta.qmax)
             .astype(dtype)
         )
     else:
         # don't trick to combine with is_unsigned, seeing ``get_quantized_dtype``
         scale = arr_metadata["scale"]
-        return np.round(arr / scale).clip(metadata.qmin, metadata.qmax).astype(dtype)
+        return (
+            np.round(arr / scale).clip(dtype_meta.qmin, dtype_meta.qmax).astype(dtype)
+        )
 
 
-def _convert_from_quantized_dtype(arr: np.ndarray, dtype_str: str):
-    metadata = _metadata_dict[dtype_str]
-    arr_metadata = arr.dtype.metadata["mgb_dtype"]
+def _convert_from_quantized_dtype(arr: np.ndarray, dtype_meta: QuantDtypeMeta):
     if not isinstance(arr, np.ndarray):
         raise ValueError("arr parameter should be instance of np.ndarray")
-    if not is_quantize(arr.dtype) or arr_metadata["name"] != metadata.name:
-        raise ValueError("arr's dtype should be a {} dtype".format(dtype_str))
-    is_unsigned = metadata.is_unsigned
-    if is_unsigned:
+    if (
+        not is_quantize(arr.dtype)
+        or arr.dtype.metadata["mgb_dtype"]["name"] != dtype_meta.cname
+    ):
+        raise ValueError("arr's dtype should be a {} dtype".format(dtype_meta))
+    arr_metadata = arr.dtype.metadata["mgb_dtype"]
+    if dtype_meta.is_unsigned:
         scale, zp = (
             arr_metadata["scale"],
             arr_metadata["zero_point"],
@@ -187,7 +243,7 @@ def convert_to_quint8(arr: np.ndarray, q: np.dtype):
     :param arr: Input ndarray.
     :param q: Target data type, should be a quint8.
     """
-    return _convert_to_quantized_dtype(arr, q, "quint8")
+    return _convert_to_quantized_dtype(arr, q, _builtin_quant_dtypes["quint8"])
 
 
 def convert_from_quint8(arr: np.ndarray):
@@ -196,7 +252,7 @@ def convert_from_quint8(arr: np.ndarray):
 
     :param arr: Input ndarray.
     """
-    return _convert_from_quantized_dtype(arr, "quint8")
+    return _convert_from_quantized_dtype(arr, _builtin_quant_dtypes["quint8"])
 
 
 def convert_to_qint8(arr: np.ndarray, q: np.dtype):
@@ -206,7 +262,7 @@ def convert_to_qint8(arr: np.ndarray, q: np.dtype):
     :param arr: Input ndarray.
     :param q: Target data type, should be a qint8.
     """
-    return _convert_to_quantized_dtype(arr, q, "qint8")
+    return _convert_to_quantized_dtype(arr, q, _builtin_quant_dtypes["qint8"])
 
 
 def convert_from_qint8(arr: np.ndarray):
@@ -215,7 +271,7 @@ def convert_from_qint8(arr: np.ndarray):
 
     :param arr: Input ndarray.
     """
-    return _convert_from_quantized_dtype(arr, "qint8")
+    return _convert_from_quantized_dtype(arr, _builtin_quant_dtypes["qint8"])
 
 
 def convert_to_qint32(arr: np.ndarray, q: np.dtype):
@@ -225,7 +281,7 @@ def convert_to_qint32(arr: np.ndarray, q: np.dtype):
     :param arr: Input ndarray.
     :param q: Target data type, should be a qint8.
     """
-    return _convert_to_quantized_dtype(arr, q, "qint32")
+    return _convert_to_quantized_dtype(arr, q, _builtin_quant_dtypes["qint32"])
 
 
 def convert_from_qint32(arr):
@@ -234,7 +290,7 @@ def convert_from_qint32(arr):
 
     :param arr: Input ndarray.
     """
-    return _convert_from_quantized_dtype(arr, "qint32")
+    return _convert_from_quantized_dtype(arr, _builtin_quant_dtypes["qint32"])
 
 
 def convert_to_quint4(arr: np.ndarray, q: np.dtype):
@@ -244,7 +300,7 @@ def convert_to_quint4(arr: np.ndarray, q: np.dtype):
     :param arr: Input ndarray.
     :param q: Target data type, should be a quint4.
     """
-    return _convert_to_quantized_dtype(arr, q, "quint4")
+    return _convert_to_quantized_dtype(arr, q, _builtin_quant_dtypes["quint4"])
 
 
 def convert_from_quint4(arr: np.ndarray):
@@ -253,7 +309,7 @@ def convert_from_quint4(arr: np.ndarray):
 
     :param arr: Input ndarray.
     """
-    return _convert_from_quantized_dtype(arr, "quint4")
+    return _convert_from_quantized_dtype(arr, _builtin_quant_dtypes["quint4"])
 
 
 def convert_to_qint4(arr: np.ndarray, q: np.dtype):
@@ -263,7 +319,7 @@ def convert_to_qint4(arr: np.ndarray, q: np.dtype):
     :param arr: Input ndarray.
     :param q: Target data type, should be a qint4.
     """
-    return _convert_to_quantized_dtype(arr, q, "qint4")
+    return _convert_to_quantized_dtype(arr, q, _builtin_quant_dtypes["qint4"])
 
 
 def convert_from_qint4(arr: np.ndarray):
@@ -272,4 +328,4 @@ def convert_from_qint4(arr: np.ndarray):
 
     :param arr: Input ndarray.
     """
-    return _convert_from_quantized_dtype(arr, "qint4")
+    return _convert_from_quantized_dtype(arr, _builtin_quant_dtypes["qint4"])
diff --git a/imperative/python/megengine/functional/nn.py b/imperative/python/megengine/functional/nn.py
index 33a8484cf08c50957468972bfc8f8c01a5f2210f..22b2a5f9355fa340053b2a0c135f8c7c671478a4 100644
--- a/imperative/python/megengine/functional/nn.py
+++ b/imperative/python/megengine/functional/nn.py
@@ -203,7 +203,7 @@ def conv_transpose2d(
     assert compute_mode == "DEFAULT" or compute_mode.name == "DEFAULT"
 
     if groups != 1:
-        raise NotImplementedError("TODO")
+        raise NotImplementedError("group transposed conv2d is not supported yet.")
 
     stride_h, stride_w = expand_hw(stride)
     pad_h, pad_w = expand_hw(padding)
diff --git a/imperative/python/megengine/jit/tracing.py b/imperative/python/megengine/jit/tracing.py
index 925cb8eea463984fdd042a8b90609553a812a1df..91c6e7d347aeaad2f8ca96755a43764a4ca1bb6a 100644
--- a/imperative/python/megengine/jit/tracing.py
+++ b/imperative/python/megengine/jit/tracing.py
@@ -13,7 +13,6 @@ import itertools
 import json
 import os
 import typing
-import warnings
 import weakref
 
 import numpy as np
diff --git a/imperative/python/megengine/module/module.py b/imperative/python/megengine/module/module.py
index df857626f5477c1fc41230b1732cfef16d22e4ce..5293ad29738c3c17749d8619c80971733177e96b 100644
--- a/imperative/python/megengine/module/module.py
+++ b/imperative/python/megengine/module/module.py
@@ -5,7 +5,6 @@
 # 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 warnings
 from abc import ABCMeta, abstractmethod
 from collections import OrderedDict
 from typing import Any, Callable, Iterable, Optional, Set, Tuple, Union
@@ -204,10 +203,9 @@ class Module(metaclass=ABCMeta):
 
         if "requires_grad" in kwargs:
             del kwargs["requires_grad"]
-            warnings.warn(
+            logger.warning(
                 "Tensor currently has no requires_grad attribute "
-                "so requires_grad argument is ignored here",
-                DeprecationWarning,
+                "so requires_grad argument is ignored here"
             )
 
         def predicate(obj) -> bool:
@@ -232,10 +230,9 @@ class Module(metaclass=ABCMeta):
 
         if "requires_grad" in kwargs:
             del kwargs["requires_grad"]
-            warnings.warn(
+            logger.warning(
                 "Tensor currently has no requires_grad attribute "
-                "so requires_grad argument is ignored here",
-                DeprecationWarning,
+                "so requires_grad argument is ignored here"
             )
 
         def predicate(obj) -> bool:
diff --git a/imperative/python/megengine/module/qat/module.py b/imperative/python/megengine/module/qat/module.py
index 82b2911cce169937b8377912b23ca4267db3429d..466ba960ddd9af4e50763478cdf2ae81c308bedc 100644
--- a/imperative/python/megengine/module/qat/module.py
+++ b/imperative/python/megengine/module/qat/module.py
@@ -7,7 +7,10 @@
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 from abc import abstractmethod
 
-from ...quantization import FakeQuantize, Observer, QConfig
+# avoid circular reference
+from ...quantization.fake_quant import FakeQuantize
+from ...quantization.observer import Observer
+from ...quantization.qconfig import QConfig
 from ...tensor import Tensor
 from ..module import Module
 
@@ -73,19 +76,19 @@ class QATModule(Module):
         # do observer
         if observer is None:
             oup = target
-            q_dict = None
+            qparams = None
         else:
             oup = observer(target)
-            q_dict = observer.get_qparams()
+            qparams = observer.get_qparams()
         # do fake quant
         if fake_quant is not None:
-            oup = fake_quant(oup, q_dict)
+            oup = fake_quant(oup, qparams)
             # use qparams of fake_quant if have.
             if hasattr(fake_quant, "get_qparams"):
-                q_dict = fake_quant.get_qparams()
+                qparams = fake_quant.get_qparams()
         # set to tensor qparams.
-        if q_dict is not None:
-            oup.q_dict.update(q_dict)
+        if qparams is not None:
+            oup.qparams.update(qparams)
         return oup
 
     def apply_quant_weight(self, target: Tensor):
@@ -118,7 +121,7 @@ class QATModule(Module):
         Get weight's quantization dtype as the method from ``qconfig``.
         """
         return self._get_method_result(
-            "get_dtype", self.weight_fake_quant, self.weight_observer
+            "get_quantized_dtype", self.weight_fake_quant, self.weight_observer
         )
 
     def get_activation_dtype(self):
@@ -126,7 +129,7 @@ class QATModule(Module):
         Get activation's quantization dtype as the method from ``qconfig``.
         """
         return self._get_method_result(
-            "get_dtype", self.act_fake_quant, self.act_observer
+            "get_quantized_dtype", self.act_fake_quant, self.act_observer
         )
 
     def get_weight_qparams(self):
diff --git a/imperative/python/megengine/quantization/__init__.py b/imperative/python/megengine/quantization/__init__.py
index b21b3a636e0bae42ea50000e4fd9a1d108980e6f..0407cd6a58c81f1293301152d33899d8e2730d49 100644
--- a/imperative/python/megengine/quantization/__init__.py
+++ b/imperative/python/megengine/quantization/__init__.py
@@ -7,8 +7,7 @@
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 
 from .fake_quant import FakeQuantize
-from .internal_fake_quant import *
-from .observer import HistogramObserver, Observer
+from .observer import Observer
 from .qconfig import (
     QConfig,
     calibration_qconfig,
@@ -20,4 +19,15 @@ from .qconfig import (
     sync_ema_fakequant_qconfig,
     tqt_qconfig,
 )
-from .utils import QuantMode
+from .quantize import (
+    apply_easy_quant,
+    disable_fake_quant,
+    disable_observer,
+    enable_fake_quant,
+    enable_observer,
+    propagate_qconfig,
+    quantize,
+    quantize_qat,
+    reset_qconfig,
+)
+from .utils import QParams, QuantMode, create_qparams
diff --git a/imperative/python/megengine/quantization/fake_quant.py b/imperative/python/megengine/quantization/fake_quant.py
index 15d584db29d080b64a00da5a8b25623ec20ae415..d115c64615e7db3b7c11025a72ac31834db1dcde 100644
--- a/imperative/python/megengine/quantization/fake_quant.py
+++ b/imperative/python/megengine/quantization/fake_quant.py
@@ -6,40 +6,48 @@
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 import math
+from typing import Union
 
 from .. import functional as F
-from ..core.tensor.dtype import _metadata_dict, get_quantized_dtype
+from ..core.tensor.dtype import QuantDtypeMeta, _builtin_quant_dtypes
+from ..logger import get_logger
 from ..module import Module
-from ..tensor import Parameter, Tensor
-from .utils import QuantMode, fake_quant_tensor, get_qparam_dict, tqt_forward
+from ..tensor import Parameter
+from .utils import (
+    QParams,
+    QParamsModuleMixin,
+    QuantMode,
+    create_qparams,
+    fake_quant_tensor,
+    tqt_forward,
+)
 
+logger = get_logger(__name__)
 
-class _FakeQuantize(Module):
-    r"""
-    A Basic Fake Quant module.
-
-    :param dtype: a string indicating the target quantization type of input.
-    :param narrow_range: whether the absolute value of ``qmin`` is the same as ``qmax``,
-        instead of 1 greater. Usually True for weight and False for activation.
-    :param enable: whether do ``normal_forward`` or ``fake_quant_forward``.
-    """
 
+class _FakeQuantize(Module):
     def __init__(
-        self, dtype: str, narrow_range: bool = False, enable: bool = True, **kwargs
+        self, dtype: Union[str, QuantDtypeMeta], enable: bool = True, **kwargs
     ):
         super().__init__()
-        if not dtype in _metadata_dict.keys():
-            raise ValueError(
-                "unknown dtype: {}, only support {}".format(
-                    dtype, _metadata_dict.keys()
+        if isinstance(dtype, str):
+            if not dtype in _builtin_quant_dtypes:
+                raise ValueError(
+                    "unknown dtype: {}, only support {}".format(
+                        dtype, _builtin_quant_dtypes.keys()
+                    )
                 )
+            dtype = _builtin_quant_dtypes[dtype]
+        if "narrow_range" in kwargs:
+            del kwargs["narrow_range"]
+            logger.warning(
+                "FakeQuantize currently has no narrow_range param "
+                "so it is ignored here",
+                exc_info=DeprecationWarning,
             )
         self.dtype = dtype
-        self.narrow_range = narrow_range
-        self.qmin = (
-            -_metadata_dict[dtype].qmax if narrow_range else _metadata_dict[dtype].qmin
-        )
-        self.qmax = _metadata_dict[dtype].qmax
+        self.qmin = dtype.qmin
+        self.qmax = dtype.qmax
         self.enabled = enable
 
     def enable(self):
@@ -48,61 +56,64 @@ class _FakeQuantize(Module):
     def disable(self):
         self.enabled = False
 
-    def fake_quant_forward(self, inp, q_dict=None):
-        return inp
+    def fake_quant_forward(self, inp, qparams: QParams = None):
+        raise NotImplementedError
 
-    def normal_foward(self, inp, q_dict=None):
+    def normal_foward(self, inp, qparams: QParams = None):
         return inp
 
-    def forward(self, inp, q_dict=None):
+    def forward(self, inp, qparams: QParams = None):
         if self.enabled:
-            return self.fake_quant_forward(inp, q_dict=q_dict)
+            return self.fake_quant_forward(inp, qparams=qparams)
         else:
-            return self.normal_foward(inp, q_dict=q_dict)
+            return self.normal_foward(inp, qparams=qparams)
 
 
-class TQT(_FakeQuantize):
+class TQT(_FakeQuantize, QParamsModuleMixin):
     r"""
     TQT: https://arxiv.org/abs/1903.08066 Trained Quantization Thresholds
     for Accurate and Efficient Fixed-Point Inference of Deep Neural Networks.
+
+    :param dtype: a string or :class:`~.QuantDtypeMeta` indicating the target
+    quantization dtype of input.
+    :param enable: whether do ``normal_forward`` or ``fake_quant_forward``.
     """
 
     def __init__(
-        self, dtype: str, narrow_range: bool = False, enable: bool = True, **kwargs
+        self, dtype: Union[str, QuantDtypeMeta], enable: bool = True, **kwargs
     ):
-        super().__init__(dtype, narrow_range, enable, **kwargs)
+        super().__init__(dtype, enable, **kwargs)
         self.scale = Parameter(0.0, dtype="float32")
 
-    def fake_quant_forward(self, inp, q_dict=None):
+    def fake_quant_forward(self, inp, qparams: QParams = None):
         # when enable, TQT will do fakequant forward, finetune the scale
         return tqt_forward(self.qmin, self.qmax, inp, self.scale)
 
-    def get_qparams(self):
-        q_dict = get_qparam_dict(QuantMode.SYMMERTIC)
-        q_dict["scale"] = 2 ** self.scale.detach()
-        return q_dict
-
-    def set_qparams(self, q_dict):
+    def set_qparams(self, qparams: QParams):
         assert (
-            q_dict["mode"] == QuantMode.SYMMERTIC
+            qparams.mode == QuantMode.SYMMERTIC
         ), "only symmetric quantization is supported by TQT"
-        if "scale" not in q_dict or q_dict["scale"] is None:
+        if qparams.scale is None:
             raise AssertionError("Can not get an initialized scale")
-        self.scale._reset(F.log(q_dict["scale"]) / math.log(2))
+        self.scale[...] = F.log(qparams.scale) / math.log(2)
 
-    def get_dtype(self):
-        q_dict = self.get_qparams()
-        scale = None if "scale" not in q_dict else q_dict["scale"].numpy()
-        zero_point = (
-            None if "zero_point" not in q_dict else q_dict["zero_point"].numpy()
-        )
-        return get_quantized_dtype(self.dtype, scale, zero_point)
+    def get_qparams(self):
+        return create_qparams(QuantMode.SYMMERTIC, self.dtype, scale=2 ** self.scale)
 
 
 class FakeQuantize(_FakeQuantize):
     r"""
     A module to do quant and dequant according to observer's scale and zero_point.
+
+    :param dtype: a string or :class:`~.QuantDtypeMeta` indicating the target
+    quantization dtype of input.
+    :param enable: whether do ``normal_forward`` or ``fake_quant_forward``.
     """
 
-    def fake_quant_forward(self, inp, q_dict=None):
-        return fake_quant_tensor(inp, self.qmin, self.qmax, q_dict)
+    def fake_quant_forward(self, inp, qparams: QParams = None):
+        assert (
+            qparams.dtype_meta is self.dtype
+        ), "input qparams' dtype is not equal to self.dtype.\nqparams.dtype_meta={}\nself.dtype={}".format(
+            qparams.dtype_meta, self.dtype
+        )
+        return fake_quant_tensor(inp, qparams)
diff --git a/imperative/python/megengine/quantization/internal_fake_quant.py b/imperative/python/megengine/quantization/internal_fake_quant.py
index 013ddde73e87bffe502d5e4615a59723d237ad5c..a46b40d86f0e42d4cd2f96d2094a094cb6f74221 100644
--- a/imperative/python/megengine/quantization/internal_fake_quant.py
+++ b/imperative/python/megengine/quantization/internal_fake_quant.py
@@ -16,4 +16,6 @@ from ..autodiff import Function
 from .fake_quant import _FakeQuantize
 from .observer import MinMaxObserver
 from .qconfig import QConfig
+from .utils import QParams
+
 
diff --git a/imperative/python/megengine/quantization/observer.py b/imperative/python/megengine/quantization/observer.py
index bc4f0cf5f79236f85a45f60ba1c056e1bcf42c1b..dbeaf821b0b744cfbae347ae4f61a912c0a3fa71 100644
--- a/imperative/python/megengine/quantization/observer.py
+++ b/imperative/python/megengine/quantization/observer.py
@@ -8,51 +8,51 @@
 import math
 from abc import abstractmethod
 from copy import deepcopy
+from typing import Union
 
 import numpy as np
 
 from .. import functional as F
-from ..core.tensor.dtype import _metadata_dict, get_quantized_dtype
+from ..core.tensor.dtype import QuantDtypeMeta, _builtin_quant_dtypes
 from ..distributed import WORLD, get_rank, is_distributed
 from ..functional.distributed import all_reduce_max, all_reduce_min
+from ..logger import get_logger
 from ..module import Module
 from ..tensor import Tensor
-from .utils import QuantMode, get_qparam_dict
+from .utils import QParams, QParamsModuleMixin, QuantMode, create_qparams
 
+logger = get_logger(__name__)
 
-class Observer(Module):
+
+class Observer(Module, QParamsModuleMixin):
     r"""
     A base class for Observer Module.
 
     :param dtype: a string indicating to collect scale and zero_point of which dtype.
-    :param narrow_range: whether the absolute value of ``qmin`` is the same as ``qmax``,
-        instead of 1 greater. Usually True for weight and False for activation.
     """
 
-    def __init__(self, dtype: str, narrow_range: bool = False, **kwargs):
+    def __init__(self, dtype: Union[str, QuantDtypeMeta], **kwargs):
         super().__init__()
-        if dtype not in _metadata_dict.keys():
-            raise ValueError(
-                "unknown dtype: {}, only support {}".format(
-                    dtype, _metadata_dict.keys()
+        if isinstance(dtype, str):
+            if not dtype in _builtin_quant_dtypes:
+                raise ValueError(
+                    "unknown dtype: {}, only support {}".format(
+                        dtype, _builtin_quant_dtypes.keys()
+                    )
                 )
+            dtype = _builtin_quant_dtypes[dtype]
+        if "narrow_range" in kwargs:
+            del kwargs["narrow_range"]
+            logger.warning(
+                "FakeQuantize currently has no narrow_range param "
+                "so it is ignored here",
+                exc_info=DeprecationWarning,
             )
         self.dtype = dtype
-        self.narrow_range = narrow_range
-        self.qmin = (
-            -_metadata_dict[dtype].qmax if narrow_range else _metadata_dict[dtype].qmin
-        )
-        self.qmax = _metadata_dict[dtype].qmax
+        self.qmin = dtype.qmin
+        self.qmax = dtype.qmax
         self.enabled = True
 
-    def get_dtype(self):
-        q_dict = self.get_qparams()
-        numpy_scale = None if "scale" not in q_dict else q_dict["scale"].numpy()
-        numpy_zero_point = (
-            None if "zero_point" not in q_dict else q_dict["zero_point"].numpy()
-        )
-        return get_quantized_dtype(self.dtype, numpy_scale, numpy_zero_point)
-
     def enable(self):
         self.enabled = True
 
@@ -70,21 +70,16 @@ class Observer(Module):
     def forward(self, x):
         pass
 
-    @abstractmethod
-    def get_qparams(self, **kwargs):
-        pass
-
 
 class MinMaxObserver(Observer):
     def __init__(
         self,
-        mode=QuantMode.SYMMERTIC,
-        eps=0.00001,
-        dtype="qint8",
-        narrow_range: bool = False,
+        mode: QuantMode = QuantMode.SYMMERTIC,
+        eps: float = 0.00001,
+        dtype: Union[str, QuantDtypeMeta] = "qint8",
         **kwargs
     ):
-        super().__init__(dtype, narrow_range, **kwargs)
+        super().__init__(dtype, **kwargs)
         self.mode = mode
         self.min_val = Tensor(np.finfo(np.float32).max, dtype=np.float32)
         self.max_val = Tensor(np.finfo(np.float32).min, dtype=np.float32)
@@ -93,26 +88,22 @@ class MinMaxObserver(Observer):
     def _calculate_qparams(self, inp_min_val, inp_max_val):
         min_val = F.minimum(0.0, inp_min_val)
         max_val = F.maximum(0.0, inp_max_val)
-        q_dict = get_qparam_dict(self.mode)
-        q_dict["min_val"] = inp_min_val
-        q_dict["max_val"] = inp_max_val
-        q_dict["enable_observer"] = self.enable
         if self.mode == QuantMode.SYMMERTIC:
             symmetric_max_vals = F.maximum(-min_val, max_val)
             # use maximun to avoid scale too small at the begin
-            q_dict["scale"] = F.maximum(
+            scale = F.maximum(
                 symmetric_max_vals / ((self.qmax - self.qmin) / 2), self.scale_limit
             )
-            # zero_point = self.zero_point
+            zero_point = None
         else:
             # use maximun to avoid scale too small at the begin
-            q_dict["scale"] = F.maximum(
+            scale = F.maximum(
                 (max_val - min_val) / (self.qmax - self.qmin), self.scale_limit
             )
             # caculate zero_point
-            q_dict["zero_point"] = self.qmin - F.round(min_val / q_dict["scale"])
+            zero_point = self.qmin - F.round((min_val / scale))
 
-        return q_dict
+        return create_qparams(self.mode, self.dtype, scale=scale, zero_point=zero_point)
 
     def get_qparams(self):
         return self._calculate_qparams(self.min_val, self.max_val)
@@ -122,8 +113,8 @@ class MinMaxObserver(Observer):
             # stop gradient
             x = x_orig.detach()
             # find max and min
-            self.min_val._reset(F.minimum(self.min_val, x.min()))
-            self.max_val._reset(F.maximum(self.max_val, x.max()))
+            self.min_val[...] = F.minimum(self.min_val, x.min())
+            self.max_val[...] = F.maximum(self.max_val, x.max())
         return x_orig
 
 
@@ -137,42 +128,43 @@ class SyncMinMaxObserver(MinMaxObserver):
             else:
                 min_x = x.min()
                 max_x = x.max()
-            self.min_val._reset(F.minimum(self.min_val, min_x))
-            self.max_val._reset(F.maximum(self.max_val, max_x))
+            self.min_val[...] = F.minimum(self.min_val, min_x)
+            self.max_val[...] = F.maximum(self.max_val, max_x)
         return x_orig
 
 
 class ExponentialMovingAverageObserver(MinMaxObserver):
     def __init__(
         self,
-        momentum=0.9,
-        mode=QuantMode.SYMMERTIC,
-        eps=0.00001,
-        dtype="qint8",
-        narrow_range: bool = False,
+        momentum: float = 0.9,
+        mode: QuantMode = QuantMode.SYMMERTIC,
+        eps: float = 0.00001,
+        dtype: Union[str, QuantDtypeMeta] = "qint8",
         **kwargs
     ):
-        super().__init__(mode, eps, dtype, narrow_range, **kwargs)
+        super().__init__(mode, eps, dtype, **kwargs)
         self.momentum = Tensor(momentum, dtype="float32")
+        # used to avoid if-clauses in the first forward which is not supported
+        # in trace mode.
         self.runtime_momentum = Tensor(0.0)
 
     def set_momentum(self, momentum):
-        self.momentum = Tenosr(momentum, dtype="float32")
+        self.momentum = Tensor(momentum, dtype="float32")
 
     def forward(self, x_orig):
         if self.enabled:
             # stop gradient
             x = x_orig.detach()
             # Exponential Moving Average
-            self.min_val._reset(
+            self.min_val[...] = (
                 self.min_val * self.runtime_momentum
                 + (1 - self.runtime_momentum) * x.min()
             )
-            self.max_val._reset(
+            self.max_val[...] = (
                 self.max_val * self.runtime_momentum
                 + (1 - self.runtime_momentum) * x.max()
             )
-            self.runtime_momentum = self.momentum
+            self.runtime_momentum[...] = self.momentum
 
         return x_orig
 
@@ -187,33 +179,34 @@ class SyncExponentialMovingAverageObserver(ExponentialMovingAverageObserver):
             else:
                 min_x = x.min()
                 max_x = x.max()
-            self.min_val._reset(
+            self.min_val[...] = (
                 self.min_val * self.runtime_momentum
                 + (1 - self.runtime_momentum) * min_x
             )
-            self.max_val._reset(
+            self.max_val[...] = (
                 self.max_val * self.runtime_momentum
                 + (1 - self.runtime_momentum) * max_x
             )
-            self.runtime_momentum = self.momentum
+            self.runtime_momentum[...] = self.momentum
         return x_orig
 
 
 class HistogramObserver(MinMaxObserver):
     def __init__(
         self,
-        bins=2048,
-        upsample_rate=128,
-        mode=QuantMode.SYMMERTIC,
-        eps=0.00001,
-        dtype="qint8",
-        narrow_range: bool = False,
+        bins: int = 2048,
+        upsample_rate: int = 128,
+        mode: QuantMode = QuantMode.SYMMERTIC,
+        eps: float = 0.00001,
+        dtype: Union[str, QuantDtypeMeta] = "qint8",
         **kwargs
     ):
-        super().__init__(mode, eps, dtype, narrow_range, **kwargs)
+        super().__init__(mode, eps, dtype, **kwargs)
         self.bins = bins
         self.upsample_rate = upsample_rate
-        self.dst_nbins = _metadata_dict[dtype].qmax - _metadata_dict[dtype].qmin + 1
+        self.dst_nbins = (
+            _builtin_quant_dtypes[dtype].qmax - _builtin_quant_dtypes[dtype].qmin + 1
+        )
         self.histogram = Tensor([-1] + [0.0] * (bins - 1), dtype="float32")
 
     def _non_linear_param_search(self):
@@ -450,34 +443,45 @@ class HistogramObserver(MinMaxObserver):
 
 class PassiveObserver(Observer):
     r"""
-    This class can be set :attr:`scale` derectly.
+    An Observer that supports setting :attr:`scale` directly.
     """
 
-    def __init__(self, dtype: str, narrow_range: bool = False, **kwargs):
-        super().__init__(dtype, narrow_range, **kwargs)
-        self.q_dict = None
+    def __init__(self, dtype: Union[str, QuantDtypeMeta], **kwargs):
+        super().__init__(dtype, **kwargs)
+        self.qparams = None
         self.orig_scale = None
 
     @property
     def scale(self):
-        return self.q_dict["scale"]
+        return self.qparams.scale
 
     @scale.setter
-    def scale(self, value):
-        assert value > 0
-        self.q_dict["scale"][...] = Tensor(value)
+    def scale(self, value: np.ndarray):
+        assert np.all(value > 0)
+        self.qparams.scale[...] = Tensor(value)
 
     def get_qparams(self):
-        return self.q_dict
+        return self.qparams
 
-    def set_qparams(self, q_dict):
-        self.q_dict = deepcopy(q_dict)
-        if "scale" not in q_dict or q_dict["scale"] is None:
+    def set_qparams(self, qparams: QParams):
+        """
+        :param qparams: used to set initial scale.
+        """
+        self.qparams = deepcopy(qparams)
+        if qparams.scale is None:
             raise AssertionError("Can not get an initialized scale")
-        self.orig_scale = q_dict["scale"].numpy()
+        if qparams.dtype_meta is None:
+            qparams.dtype_meta = self.dtype
+        else:
+            assert (
+                qparams.dtype_meta is self.dtype
+            ), "input qparams' dtype is not equal to self.dtype.\nqparams.dtype_meta={}\nself.dtype={}".format(
+                qparams.dtype_meta, self.dtype
+            )
+        self.orig_scale = qparams.scale.numpy()
 
     def forward(self, x):
         r"""
-        Just return input because :attr:`q_dict` is set by :func:`~.apply_easy_quant`.
+        Just return input because :attr:`qparams` is set by :func:`~.apply_easy_quant`.
         """
         return x
diff --git a/imperative/python/megengine/quantization/qconfig.py b/imperative/python/megengine/quantization/qconfig.py
index a699b4b1d85043ec77d75d7d632a77e175b31882..5050045c2f62f852fe48936e02c21aba28b09f4a 100644
--- a/imperative/python/megengine/quantization/qconfig.py
+++ b/imperative/python/megengine/quantization/qconfig.py
@@ -5,6 +5,7 @@
 # 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 namedtuple
 from functools import partial
 
 from ..module import Module
@@ -19,7 +20,13 @@ from .observer import (
 )
 
 
-class QConfig:
+# use namedtuple to make class immutable, comparable and easy to print
+class QConfig(
+    namedtuple(
+        "QConfig",
+        ["weight_observer", "act_observer", "weight_fake_quant", "act_fake_quant"],
+    )
+):
     r"""
     A config class indicating how to do quantize toward :class:`~.QATModule`'s
     ``activation`` and ``weight``. See :meth:`~.QATModule.set_qconfig` for detail usage.
@@ -37,90 +44,66 @@ class QConfig:
 
         # Default EMA QConfig for QAT.
         ema_fakequant_qconfig = QConfig(
-            weight_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=True),
-            act_observer=partial(ExponentialMovingAverageObserver, dtype="qint8", narrow_range=False),
-            weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-            act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+            weight_observer=partial(MinMaxObserver, dtype="qint8_narrow"),
+            act_observer=partial(ExponentialMovingAverageObserver, dtype="qint8"),
+            weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+            act_fake_quant=partial(FakeQuantize, dtype="qint8"),
         )
 
     Each parameter is a ``class`` rather than an instance. And we recommand using ``functools.partial``
     to add initialization parameters of the ``class``, so that don't need to provide parameters in
     :meth:`~.QATModule.set_qconfig`.
 
-    Usually we set ``narrow_range`` of weight related paramters to ``True`` and of activation related
-    parameters to ``False``. For the result of multiplication and addition as ``a * b + c * d``, if
-    four variables are all -128 of dtype ``qint8``, then the result will be ``2^15`` and cause overflow.
-    Weights are commonly calculated in this way, so needed to narrow the range.
+    Usually we choose narrow version dtype (like ``qint8_narrow``) for weight related
+    paramters and normal version for activation related ones. For the result of
+    multiplication and addition as ``a * b + c * d``, if four variables are all -128 of
+    dtype ``qint8``, then the result will be ``2^15`` and cause overflow.
+    Weights are commonly calculated in this way, so need to narrow qmin to -127.
     """
 
-    def __init__(
-        self, weight_observer, act_observer, weight_fake_quant, act_fake_quant
-    ):
+    def __new__(cls, weight_observer, act_observer, weight_fake_quant, act_fake_quant):
         if isinstance(act_observer, Module) or isinstance(weight_observer, Module):
             raise ValueError(
                 "QConfig must not receive observer instance, please pass observer"
                 " class generator using `partial(Observer, ...)` instead. Use"
                 " partial(MyObserver, x=1) to override arguments to constructor if needed"
             )
-        self.weight_observer = weight_observer
-        self.act_observer = act_observer
-        self.weight_fake_quant = weight_fake_quant
-        self.act_fake_quant = act_fake_quant
-
-    def __eq__(self, other):
-        def eq(a, b):
-            if isinstance(a, partial) and isinstance(b, partial):
-                return all(
-                    [a.func == b.func, a.args == b.args, a.keywords == b.keywords]
-                )
-            else:
-                return a == b
-
-        return (
-            eq(self.weight_observer, other.weight_observer)
-            and eq(self.act_observer, other.act_observer)
-            and eq(self.weight_fake_quant, other.weight_fake_quant)
-            and eq(self.act_fake_quant, other.act_fake_quant)
+        return super().__new__(
+            cls, weight_observer, act_observer, weight_fake_quant, act_fake_quant
         )
 
 
 min_max_fakequant_qconfig = QConfig(
-    weight_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=False),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+    weight_observer=partial(MinMaxObserver, dtype="qint8_narrow"),
+    act_observer=partial(MinMaxObserver, dtype="qint8"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint8"),
 )
 
 ema_fakequant_qconfig = QConfig(
-    weight_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(
-        ExponentialMovingAverageObserver, dtype="qint8", narrow_range=False
-    ),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+    weight_observer=partial(MinMaxObserver, dtype="qint8_narrow"),
+    act_observer=partial(ExponentialMovingAverageObserver, dtype="qint8"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint8"),
 )
 
 sync_ema_fakequant_qconfig = QConfig(
-    weight_observer=partial(SyncMinMaxObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(
-        SyncExponentialMovingAverageObserver, dtype="qint8", narrow_range=False
-    ),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+    weight_observer=partial(SyncMinMaxObserver, dtype="qint8_narrow"),
+    act_observer=partial(SyncExponentialMovingAverageObserver, dtype="qint8"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint8"),
 )
 
 ema_lowbit_fakequant_qconfig = QConfig(
-    weight_observer=partial(MinMaxObserver, dtype="qint4", narrow_range=False),
-    act_observer=partial(
-        ExponentialMovingAverageObserver, dtype="qint4", narrow_range=False
-    ),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint4", narrow_range=False),
-    act_fake_quant=partial(FakeQuantize, dtype="qint4", narrow_range=False),
+    weight_observer=partial(MinMaxObserver, dtype="qint4"),
+    act_observer=partial(ExponentialMovingAverageObserver, dtype="qint4"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint4"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint4"),
 )
 
 calibration_qconfig = QConfig(
-    weight_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(HistogramObserver, dtype="qint8", narrow_range=False),
+    weight_observer=partial(MinMaxObserver, dtype="qint8_narrow"),
+    act_observer=partial(HistogramObserver, dtype="qint8"),
     weight_fake_quant=None,
     act_fake_quant=None,
 )
@@ -128,15 +111,15 @@ calibration_qconfig = QConfig(
 tqt_qconfig = QConfig(
     weight_observer=None,
     act_observer=None,
-    weight_fake_quant=partial(TQT, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(TQT, dtype="qint8", narrow_range=False),
+    weight_fake_quant=partial(TQT, dtype="qint8_narrow"),
+    act_fake_quant=partial(TQT, dtype="qint8"),
 )
 
 passive_qconfig = QConfig(
-    weight_observer=partial(PassiveObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(PassiveObserver, dtype="qint8", narrow_range=False),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+    weight_observer=partial(PassiveObserver, dtype="qint8_narrow"),
+    act_observer=partial(PassiveObserver, dtype="qint8"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint8"),
 )
 
 easyquant_qconfig = passive_qconfig
diff --git a/imperative/python/megengine/quantization/quantize.py b/imperative/python/megengine/quantization/quantize.py
index 730947c9027ebfbc4c81ba7372706acec006f434..09fa9012abc3ea298f8902b6ddb5d90cc344fa31 100644
--- a/imperative/python/megengine/quantization/quantize.py
+++ b/imperative/python/megengine/quantization/quantize.py
@@ -18,6 +18,7 @@ from ..module import qat as QAT
 from ..module import quantized as Quantized
 from ..module.qat import QATModule
 from ..module.quantized import QuantizedModule
+from ..tensor import Tensor
 from .qconfig import QConfig, ema_fakequant_qconfig
 
 
@@ -147,10 +148,10 @@ def reset_qconfig(module: Module, qconfig: QConfig, inplace: bool = True):
     if not inplace:
         module = deepcopy(module)
 
-    def safe_call(func, q_dict):
+    def safe_call(func, qparams):
         inst = func() if func is not None else None
         if inst is not None and getattr(inst, "set_qparams", None) is not None:
-            inst.set_qparams(q_dict)
+            inst.set_qparams(qparams)
         return inst
 
     def is_qat(mod: Module):
@@ -158,13 +159,13 @@ def reset_qconfig(module: Module, qconfig: QConfig, inplace: bool = True):
 
     for m in list(module._flatten(predicate=is_qat)):
         if m.with_weight:
-            weight_q_dict = m.get_weight_qparams()
-            m.weight_observer = safe_call(qconfig.weight_observer, weight_q_dict)
-            m.weight_fake_quant = safe_call(qconfig.weight_fake_quant, weight_q_dict)
+            weight_params = m.get_weight_qparams()
+            m.weight_observer = safe_call(qconfig.weight_observer, weight_params)
+            m.weight_fake_quant = safe_call(qconfig.weight_fake_quant, weight_params)
         if m.with_act:
-            act_q_dict = m.get_activation_qparams()
-            m.act_observer = safe_call(qconfig.act_observer, act_q_dict)
-            m.act_fake_quant = safe_call(qconfig.act_fake_quant, act_q_dict)
+            act_params = m.get_activation_qparams()
+            m.act_observer = safe_call(qconfig.act_observer, act_params)
+            m.act_fake_quant = safe_call(qconfig.act_fake_quant, act_params)
 
     return module
 
@@ -202,7 +203,9 @@ def hook_qat_module(module: Module, func: Callable):
     return hooks
 
 
-def apply_easy_quant(module, data, start=0.8, stop=1.2, num=40):
+def apply_easy_quant(
+    module: Module, data: Tensor, start: float = 0.8, stop: float = 1.2, num: int = 40
+):
     r"""
     Implementation of ``EasyQuant``: https://arxiv.org/pdf/2006.16669.
     Search for optimal scales.
diff --git a/imperative/python/megengine/quantization/utils.py b/imperative/python/megengine/quantization/utils.py
index de1bb0fc3ba42a3bc5dbf41089e3835702559bd9..127a134c2bcf368603834b93b0ce2986e2dd3c9d 100644
--- a/imperative/python/megengine/quantization/utils.py
+++ b/imperative/python/megengine/quantization/utils.py
@@ -5,9 +5,10 @@
 # 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 abc
 from enum import Enum
 from functools import partial, update_wrapper, wraps
-from typing import Dict
+from typing import Union
 
 import numpy as np
 
@@ -15,7 +16,11 @@ from .. import functional as F
 from ..autodiff import Function
 from ..core._imperative_rt.core2 import apply
 from ..core.ops import builtin
-from ..core.tensor.dtype import _metadata_dict
+from ..core.tensor.dtype import (
+    QuantDtypeMeta,
+    _builtin_quant_dtypes,
+    create_quantized_dtype,
+)
 from ..tensor import Tensor
 
 
@@ -61,37 +66,100 @@ class QuantMode(Enum):
     ASYMMERTIC = 2
 
 
-qparam_dict = {
-    QuantMode.SYMMERTIC: {"mode": QuantMode.SYMMERTIC, "scale": None},
-    QuantMode.ASYMMERTIC: {
-        "mode": QuantMode.ASYMMERTIC,
-        "scale": None,
-        "zero_point": None,
-    },
+class QParams:
+    """
+    To standardize FakeQuant, Observer and Tensor's qparams format. If custom
+    qparams is needed, inherit this class and add custom ``__slots__``.
+    """
+
+    __slots__ = "mode", "dtype_meta", "scale", "zero_point"
+
+    def __init__(
+        self,
+        mode: QuantMode,
+        dtype_meta: QuantDtypeMeta,
+        scale: Tensor,
+        zero_point: Tensor,
+    ):
+        self.mode = mode
+        self.dtype_meta = dtype_meta
+        self.scale = scale
+        self.zero_point = zero_point
+
+    def update(self, qparams: "QParams"):
+        for key in self.__slots__:
+            setattr(self, key, getattr(qparams, key))
+
+    def __eq__(self, other):
+        if len(self.__slots__) != len(other.__slots__):
+            return False
+        for key in self.__slots__:
+            if not hasattr(other, key) or getattr(self, key) != getattr(other, key):
+                return False
+        return True
+
+    def __repr__(self):
+        content = ", ".join(
+            ["{}={}".format(key, getattr(self, key)) for key in self.__slots__]
+        )
+        return "QParams({})".format(content)
+
+
+class QParamsModuleMixin(abc.ABC):
+    def get_quantized_dtype(self):
+        qparams = self.get_qparams()
+        dtype = qparams.dtype_meta
+        scale = float(qparams.scale.numpy()) if qparams.scale is not None else None
+        zero_point = (
+            int(qparams.zero_point.numpy()) if qparams.zero_point is not None else None
+        )
+        return create_quantized_dtype(dtype, scale, zero_point)
+
+    @abc.abstractmethod
+    def get_qparams(self) -> QParams:
+        pass
+
+
+_builtin_qparams = {
+    QuantMode.SYMMERTIC: partial(QParams, mode=QuantMode.SYMMERTIC),
+    QuantMode.ASYMMERTIC: partial(QParams, mode=QuantMode.ASYMMERTIC),
 }
 
 
-def get_qparam_dict(mode: QuantMode):
+def create_qparams(
+    mode: QuantMode = QuantMode.SYMMERTIC,
+    dtype_meta: Union[str, QuantDtypeMeta] = None,
+    scale: Tensor = None,
+    zero_point: Tensor = None,
+):
     """
-    Return the quantization parameters dictionary according to the mode.
+    Return :class:`~.QParams` according to the mode.
     """
-    return qparam_dict.get(mode, None)
+    if isinstance(dtype_meta, str):
+        dtype_meta = _builtin_quant_dtypes[dtype_meta]
+    if mode is None:
+        return QParams(mode, dtype_meta, scale, zero_point)
+    assert isinstance(mode, QuantMode)
+    return _builtin_qparams[mode](
+        dtype_meta=dtype_meta, scale=scale, zero_point=zero_point
+    )
 
 
-def fake_quant_tensor(inp: Tensor, qmin: int, qmax: int, q_dict: Dict) -> Tensor:
+def fake_quant_tensor(inp: Tensor, qparams: QParams) -> Tensor:
     """
     Apply fake quantization to the inp tensor.
 
     :param inp: the input tensor which need to be faked.
-    :param qmin: the minimum value which the integer limit to.
-    :param qmax: the maximum value which the integer limit to.
-    :param q_dict: the quantization parameter dict.
+    :param qparams: to get mode, qmin, qmax, scale and zero_point from.
 
     """
-    scale = q_dict["scale"]
-    zero_point = Tensor([0.0], dtype=np.float32)
-    if q_dict["mode"] == QuantMode.ASYMMERTIC:
-        zero_point = q_dict["zero_point"]
+    scale = qparams.scale
+    if qparams.mode == QuantMode.ASYMMERTIC:
+        zero_point = qparams.zero_point
+    else:
+        zero_point = Tensor([0.0], dtype=np.float32)
+    qmin = qparams.dtype_meta.qmin
+    qmax = qparams.dtype_meta.qmax
 
     op = builtin.FakeQuant(qmin=qmin, qmax=qmax)
     return apply(op, inp, scale, zero_point)[0]
@@ -104,22 +172,34 @@ def fake_quant_bias(bias: Tensor, inp: Tensor, w_qat: Tensor) -> Tensor:
 
     :param bias: the bias tensor which need to be faked.
     :param inp:  the input tensor which contain the quantization parameters.
-    :param qmax: the weight tensor which contain the quantization parameters.
+    :param w_qat: the weight tensor which contain the quantization parameters.
 
     .. warning::
         Only work for symmetric quantization method now.
 
     """
     b_qat = bias
-    if hasattr(inp, "q_dict") and b_qat is not None:
-        if inp.q_dict["scale"] is not None and w_qat.q_dict["scale"] is not None:
-            # use the same mode with weight.
-            b_dict = get_qparam_dict(w_qat.q_dict["mode"])
-            b_dict["scale"] = inp.q_dict["scale"] * w_qat.q_dict["scale"]
-            # TODO: add zero_point for ASYMMERTIC mode.
-            qmax = _metadata_dict["qint32"].qmax
-            qmin = _metadata_dict["qint32"].qmin
-            b_qat = fake_quant_tensor(b_qat, qmin, qmax, b_dict)
-            b_qat.q_dict.update(b_dict)
+    if (
+        getattr(inp, "qparams", None) is not None
+        and getattr(w_qat, "qparams", None) is not None
+        and bias is not None
+    ):
+        inp_params = inp.qparams
+        w_params = w_qat.qparams
+        if inp_params.scale is not None and w_params.scale is not None:
+            assert inp_params.mode == w_params.mode, "incompatible QuantMode"
+            # TODO: support quint8 dtype.
+            assert (
+                inp_params.dtype_meta.np_dtype_str == "int8"
+                and w_params.dtype_meta.np_dtype_str == "int8"
+            ), "fake_quant_bias only support int8 like dtype now"
 
+            # use the same mode with weight.
+            # TODO: avoid hardcode
+            b_dtype = _builtin_quant_dtypes["qint32"]
+            b_param = create_qparams(
+                w_params.mode, b_dtype, scale=inp_params.scale * w_params.scale
+            )
+            b_qat = fake_quant_tensor(bias, b_param)
+            b_qat.qparams.update(b_param)
     return b_qat
diff --git a/imperative/python/megengine/tensor.py b/imperative/python/megengine/tensor.py
index 5c94189371c35ab8f8bc90c3102482d40b5df023..8f6072271d42f93b607de5c8863f4e25baaca8ef 100644
--- a/imperative/python/megengine/tensor.py
+++ b/imperative/python/megengine/tensor.py
@@ -22,6 +22,8 @@ from .logger import get_logger
 from .utils.deprecation import deprecated
 from .utils.naming import auto_naming
 
+logger = get_logger(__name__)
+
 
 class Tensor(_Tensor, ArrayMethodMixin):
     r"""
@@ -30,7 +32,7 @@ class Tensor(_Tensor, ArrayMethodMixin):
 
     grad = None
     dmap_callback = None
-    _q_dict = None
+    _qparams = None
 
     def __new__(
         cls, data, dtype=None, device=None, is_const=False, no_cache=False, name=None
@@ -50,7 +52,7 @@ class Tensor(_Tensor, ArrayMethodMixin):
 
         if isinstance(data, _Tensor):
             if dtype is not None:
-                get_logger().warning(
+                logger.warning(
                     "dtype does not work when creating a new Tensor with another Tensor"
                 )
             obj = _Tensor.__new__(cls, data)
@@ -101,10 +103,12 @@ class Tensor(_Tensor, ArrayMethodMixin):
         return super().dtype
 
     @property
-    def q_dict(self):
-        if self._q_dict is None:
-            self._q_dict = {"mode": None, "scale": None, "zero_point": None}
-        return self._q_dict
+    def qparams(self):
+        from .quantization.utils import create_qparams  # pylint: disable=all
+
+        if self._qparams is None:
+            self._qparams = create_qparams()
+        return self._qparams
 
     def numpy(self) -> np.ndarray:
         r"""
@@ -185,14 +189,29 @@ class Tensor(_Tensor, ArrayMethodMixin):
     def __getstate__(self):
         r""" __getstate__ will be called for pickle serialization or deep copy
         """
-
         state = {
-            "qdict": self.q_dict,
+            "numpy": self.numpy(),
+            "dtype": self.dtype,
+            "device": self.device.logical_name,
         }
+        if self._qparams is not None:
+            state["qparams"] = self._qparams
         return state
 
     def __setstate__(self, state):
-        self._q_dict = state.pop("qdict")
+        from .quantization.utils import create_qparams  # pylint: disable=all
+
+        if "qdict" in state:
+            qparams = state.pop("qdict")
+            logger.warning(
+                "Tensor's 'qdict' state is depreciated. Use 'qparams' instead"
+            )
+        elif "qparams" in state:
+            qparams = state.pop("qparams")
+        else:
+            qparams = None
+        self._reset(Tensor(state.pop("numpy"), state.pop("dtype"), state.pop("device")))
+        self._qparams = qparams
 
 
 tensor = Tensor
diff --git a/imperative/python/test/unit/core/test_dtype_quant.py b/imperative/python/test/unit/core/test_dtype_quant.py
index 20e53dd7bf7b98fee67406592f162fca3e308017..594d86e5abd3b3c3820785d391886d503dce320f 100644
--- a/imperative/python/test/unit/core/test_dtype_quant.py
+++ b/imperative/python/test/unit/core/test_dtype_quant.py
@@ -14,7 +14,7 @@ import pytest
 import megengine.core.tensor.megbrain_graph as G
 from megengine.core.ops import builtin as ops
 from megengine.core.tensor.dtype import (
-    _metadata_dict,
+    _builtin_quant_dtypes,
     convert_from_qint4,
     convert_from_qint8,
     convert_from_quint4,
@@ -76,10 +76,10 @@ def _get_compiled_result(inp, dtype, shape, device, calc_func=None):
 
 
 def _check_result_attr(oup, dtype, dtype_str, is_unsigned=True):
-    metadata = _metadata_dict[dtype_str]
+    metadata = _builtin_quant_dtypes[dtype_str]
     assert "mgb_dtype" in oup.dtype.metadata
     assert is_quantize(oup.dtype)
-    np.testing.assert_equal(oup.dtype.metadata["mgb_dtype"]["name"], metadata.name)
+    np.testing.assert_equal(oup.dtype.metadata["mgb_dtype"]["name"], metadata.cname)
     np.testing.assert_allclose(get_scale(oup.dtype), get_scale(dtype))
     if is_unsigned:
         np.testing.assert_equal(get_zero_point(oup.dtype), get_zero_point(dtype))
diff --git a/imperative/python/test/unit/core/test_serialization.py b/imperative/python/test/unit/core/test_serialization.py
index 72e79c5c81a903012bce177292ecf2c4a6eacd34..edd5e6f7172401e239d0b18e5c4d9c51fa0e3bb4 100644
--- a/imperative/python/test/unit/core/test_serialization.py
+++ b/imperative/python/test/unit/core/test_serialization.py
@@ -65,9 +65,9 @@ def test_tensor_serialization():
 
     with TemporaryFile() as f:
         a = Tensor(0)
-        a.q_dict["scale"] = Tensor(1.0)
+        a.qparams.scale = Tensor(1.0)
         pickle.dump(a, f)
         f.seek(0)
         b = pickle.load(f)
-        assert isinstance(b.q_dict["scale"], Tensor)
-        np.testing.assert_equal(b.q_dict["scale"].numpy(), 1.0)
+        assert isinstance(b.qparams.scale, Tensor)
+        np.testing.assert_equal(b.qparams.scale.numpy(), 1.0)
diff --git a/imperative/python/test/unit/core/test_tensor_wrapper.py b/imperative/python/test/unit/core/test_tensor_wrapper.py
index 099dcccae6b1e1d47495b2ae478e13b69d131c1b..52fc08f5dab71fdbad9176288061161a5df994ea 100644
--- a/imperative/python/test/unit/core/test_tensor_wrapper.py
+++ b/imperative/python/test/unit/core/test_tensor_wrapper.py
@@ -6,6 +6,8 @@
 # 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
+
 import numpy as np
 
 from megengine.core.tensor.dtype import get_scale, get_zero_point, qint8, quint8
@@ -86,3 +88,23 @@ def test_as_type():
     b = a.astype(quint8(0.3, 128))
     np.testing.assert_almost_equal(get_scale(b.dtype), 0.3)
     np.testing.assert_equal(get_zero_point(b.dtype), 128)
+
+
+def test_qparams():
+    x = Tensor(1)
+    assert x.qparams.scale is None
+    x.qparams.scale = Tensor(1.0)
+    assert x.qparams.scale.numpy() == 1.0
+    x2 = copy.copy(x)
+    assert x.qparams is x2.qparams and x2.qparams.scale.numpy() == 1.0
+    x3 = copy.deepcopy(x)
+    assert x.qparams is not x3.qparams and x3.qparams.scale.numpy() == 1.0
+
+
+def test_name():
+    x = Tensor(0)
+    assert x.name == ""
+    x.name = "x"
+    assert x.name == "x"
+    x = Tensor(0, name="x")
+    assert x.name == "x"
diff --git a/imperative/python/test/unit/functional/test_tensor.py b/imperative/python/test/unit/functional/test_tensor.py
index b2898c0fab029dee3980e7f0d33a66ba72b381f5..da6825ff30f2749070079cdc128b05dee70f3439 100644
--- a/imperative/python/test/unit/functional/test_tensor.py
+++ b/imperative/python/test/unit/functional/test_tensor.py
@@ -406,28 +406,3 @@ def test_copy_d2h():
 def test_copy_d2d():
     copy_test("gpu0", "gpu1")
     copy_test("gpu0:0", "gpu0:1")
-
-
-def test_name():
-    x = tensor(0)
-    assert x.name == ""
-    x.name = "x"
-    assert x.name == "x"
-    x = tensor(0, name="x")
-    assert x.name == "x"
-
-
-def test_q_dict():
-    x = tensor(1)
-    assert x.q_dict["scale"] is None
-    x.q_dict["scale"] = tensor(1.0)
-
-    y = tensor(1)
-    assert y.q_dict["scale"] is None
-    y.q_dict["scale"] = tensor(2.0)
-
-    assert x.q_dict["scale"].numpy() == 1.0
-    assert y.q_dict["scale"].numpy() == 2.0
-
-    z = x + y
-    assert z.q_dict["scale"] is None
diff --git a/imperative/python/test/unit/quantization/test_fake_quant.py b/imperative/python/test/unit/quantization/test_fake_quant.py
index a11edff38eb1d5748bd2fdbbb1dcb2b76b005eda..ccb2e570438e021a2c57ba4420ca15481ddcc2c7 100644
--- a/imperative/python/test/unit/quantization/test_fake_quant.py
+++ b/imperative/python/test/unit/quantization/test_fake_quant.py
@@ -12,9 +12,15 @@ import pytest
 import megengine as mge
 from megengine import tensor
 from megengine.core.autodiff.grad import Function, Grad
+from megengine.core.tensor.dtype import QuantDtypeMeta
 from megengine.core.tensor.utils import make_shape_tuple
 from megengine.quantization.internal_fake_quant import *
-from megengine.quantization.utils import QuantMode, fake_quant_tensor, tqt_forward
+from megengine.quantization.utils import (
+    QuantMode,
+    create_qparams,
+    fake_quant_tensor,
+    tqt_forward,
+)
 
 
 class TQT_numpy:
@@ -111,16 +117,14 @@ def fake_quant_tensor_gt(inp, scale, zero_point, qmin, qmax):
 def test_fakequant():
     qmin = -126
     qmax = 129
+    test_dtype = QuantDtypeMeta("test_qint8", None, "int8", qmin, qmax)
 
     def run(zero_point, scale):
-        q_dict = {}
-        q_dict["mode"] = QuantMode.ASYMMERTIC
-        q_dict["scale"] = scale
-        q_dict["zero_point"] = zero_point
+        qparams = create_qparams(QuantMode.ASYMMERTIC, test_dtype, scale, zero_point)
         inp_data = np.random.uniform(low=-512.0, high=512.0, size=(1, 32, 32, 32))
         inp = tensor(inp_data, dtype=np.float32)
         # test forward
-        oup = fake_quant_tensor(inp, qmin, qmax, q_dict).numpy()
+        oup = fake_quant_tensor(inp, qparams).numpy()
         oup_gt = fake_quant_tensor_gt(inp, scale, zero_point, qmin, qmax).numpy()
         assert np.allclose(oup, oup_gt)
         assert oup.shape == oup_gt.shape
@@ -128,7 +132,7 @@ def test_fakequant():
         # test backward
         x = tensor(inp_data, dtype=np.float32)
         grad = Grad().wrt(x, callback=_save_to(x))
-        y = fake_quant_tensor(x, qmin, qmax, q_dict)
+        y = fake_quant_tensor(x, qparams)
         grad(y, tensor(F.ones_like(x)))
 
         x1 = tensor(inp_data, dtype=np.float32)
diff --git a/imperative/python/test/unit/quantization/test_module.py b/imperative/python/test/unit/quantization/test_module.py
index 12e0d27c4d758376c2fa191e928bb8005b7467b0..cfdf03448a6777f4ba627abbccda487694118d4d 100644
--- a/imperative/python/test/unit/quantization/test_module.py
+++ b/imperative/python/test/unit/quantization/test_module.py
@@ -10,7 +10,13 @@ import megengine.module.qat as QAT
 import megengine.module.quantized as Q
 from megengine import Parameter, Tensor
 from megengine.core.tensor import dtype
-from megengine.quantization import FakeQuantize, MinMaxObserver, QConfig
+from megengine.quantization import (
+    FakeQuantize,
+    MinMaxObserver,
+    QConfig,
+    QuantMode,
+    create_qparams,
+)
 from megengine.quantization.quantize import (
     disable_fake_quant,
     disable_observer,
@@ -18,10 +24,10 @@ from megengine.quantization.quantize import (
 )
 
 min_max_fakequant_qconfig = QConfig(
-    weight_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=True),
-    act_observer=partial(MinMaxObserver, dtype="qint8", narrow_range=False),
-    weight_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=True),
-    act_fake_quant=partial(FakeQuantize, dtype="qint8", narrow_range=False),
+    weight_observer=partial(MinMaxObserver, dtype="qint8_narrow"),
+    act_observer=partial(MinMaxObserver, dtype="qint8"),
+    weight_fake_quant=partial(FakeQuantize, dtype="qint8_narrow"),
+    act_fake_quant=partial(FakeQuantize, dtype="qint8"),
 )
 
 inp_scale = np.float32(np.random.rand() + 1)
@@ -111,7 +117,7 @@ def test_dequant_stub():
 
     x = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x = fake_quant_act(x, inp_scale)
-    x.q_dict["scale"] = inp_scale
+    x.qparams.scale = inp_scale
 
     normal = normal_net(x)
     qat_without_fakequant = qat_from_float(x)
@@ -146,12 +152,12 @@ def test_elemwise(kind):
     x1_scale = np.float32(np.random.rand() + 1)
     x1 = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x1 = fake_quant_act(x1, x1_scale)
-    x1.q_dict["scale"] = x1_scale
+    x1.qparams.scale = x1_scale
 
     x2_scale = np.float32(np.random.rand() + 1)
     x2 = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x2 = fake_quant_act(x2, x2_scale)
-    x2.q_dict["scale"] = x2_scale
+    x2.qparams.scale = x2_scale
 
     x1_int8 = quant(x1, x1_scale)
     x2_int8 = quant(x2, x2_scale)
@@ -187,7 +193,7 @@ def test_linear():
 
     x = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x = fake_quant_act(x, inp_scale)
-    x.q_dict["scale"] = inp_scale
+    x.qparams.update(create_qparams(QuantMode.SYMMERTIC, "qint8", inp_scale))
 
     x_int8 = quant(x, inp_scale)
 
@@ -230,7 +236,7 @@ def test_conv(module):
 
     x = mge.tensor(np.random.normal(size=(1, 3, 3, 3)).astype("float32"))
     x = fake_quant_act(x, inp_scale)
-    x.q_dict["scale"] = inp_scale
+    x.qparams.update(create_qparams(QuantMode.SYMMERTIC, "qint8", inp_scale))
 
     x_int8 = quant(x, inp_scale)
 
diff --git a/imperative/python/test/unit/quantization/test_observer.py b/imperative/python/test/unit/quantization/test_observer.py
index 33e4f964b29c0b17278159c1b74f3ade79ebca74..bd306244cb68d50f7c50df919322c9c31f8d57c5 100644
--- a/imperative/python/test/unit/quantization/test_observer.py
+++ b/imperative/python/test/unit/quantization/test_observer.py
@@ -6,6 +6,7 @@ import pytest
 import megengine as mge
 import megengine.distributed as dist
 from megengine.distributed.helper import get_device_count_by_fork
+from megengine.quantization import QuantMode, create_qparams
 from megengine.quantization.observer import (
     ExponentialMovingAverageObserver,
     HistogramObserver,
@@ -56,14 +57,14 @@ def test_histogram_observer():
 
 
 def test_passive_observer():
-    q_dict = {"scale": mge.tensor(1.0)}
+    qparams = create_qparams(QuantMode.SYMMERTIC, "qint8", mge.tensor(1.0))
     m = PassiveObserver("qint8")
-    m.set_qparams(q_dict)
+    m.set_qparams(qparams)
     assert m.orig_scale == 1.0
-    assert m.scale == 1.0
-    m.scale = 2.0
-    assert m.scale == 2.0
-    assert m.get_qparams() == {"scale": mge.tensor(2.0)}
+    assert m.scale.numpy() == 1.0
+    assert m.get_qparams().dtype_meta == qparams.dtype_meta
+    assert m.get_qparams().scale == qparams.scale
+    assert m.get_qparams() == qparams
 
 
 @pytest.mark.require_ngpu(2)
diff --git a/imperative/python/test/unit/quantization/test_op.py b/imperative/python/test/unit/quantization/test_op.py
index 20e5b2fc608db5713f44a3b72e56ffefdad31f67..2095565622794ef07af84649fd9711ddb4ac4155 100644
--- a/imperative/python/test/unit/quantization/test_op.py
+++ b/imperative/python/test/unit/quantization/test_op.py
@@ -6,6 +6,7 @@ import megengine.functional as F
 from megengine.core.tensor import dtype
 from megengine.distributed.helper import get_device_count_by_fork
 from megengine.functional.elemwise import _elemwise_multi_type, _elwise
+from megengine.quantization import QuantMode, create_qparams
 
 
 def quant(x, scale):
@@ -26,13 +27,13 @@ def test_elemwise(kind):
     x1 = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x1_scale = np.float32(np.random.rand() + 1)
     x1 = fake_quant(x1, x1_scale)
-    x1.q_dict["scale"] = x1_scale
+    x1.qparams.update(create_qparams(QuantMode.SYMMERTIC, "qint8", x1_scale))
     x1_int8 = quant(x1, x1_scale)
 
     x2 = mge.tensor(np.random.normal(size=(3, 3)).astype("float32"))
     x2_scale = np.float32(np.random.rand() + 1)
     x2 = fake_quant(x2, x2_scale)
-    x2.q_dict["scale"] = x2_scale
+    x2.qparams.update(create_qparams(QuantMode.SYMMERTIC, "qint8", x2_scale))
     x2_int8 = quant(x2, x2_scale)
 
     output_scale = np.float32(np.random.rand() + 1)
diff --git a/imperative/python/test/unit/quantization/test_qconfig.py b/imperative/python/test/unit/quantization/test_qconfig.py
deleted file mode 100644
index 92b0150f5014d3daef5c6c37b2ee1f728f3795c2..0000000000000000000000000000000000000000
--- a/imperative/python/test/unit/quantization/test_qconfig.py
+++ /dev/null
@@ -1,14 +0,0 @@
-from functools import partial
-
-from megengine.quantization import QConfig, tqt_qconfig
-from megengine.quantization.fake_quant import TQT
-
-
-def test_equal():
-    qconfig = QConfig(
-        weight_observer=None,
-        act_observer=None,
-        weight_fake_quant=partial(TQT, dtype="qint8", narrow_range=True),
-        act_fake_quant=partial(TQT, dtype="qint8", narrow_range=False),
-    )
-    assert qconfig == tqt_qconfig
diff --git a/imperative/python/test/unit/quantization/test_quantize.py b/imperative/python/test/unit/quantization/test_quantize.py
index ed561bc19760cb6ca916806c8d941e80bef2173f..c77ba7823cddb86e46fb4acae29d4b9b97ab81dd 100644
--- a/imperative/python/test/unit/quantization/test_quantize.py
+++ b/imperative/python/test/unit/quantization/test_quantize.py
@@ -33,7 +33,7 @@ from megengine.quantization.quantize import (
 )
 
 
-class Net(Float.Module):
+class FloatNet(Float.Module):
     def __init__(self):
         super().__init__()
         self.quant = Float.QuantStub()
@@ -113,25 +113,25 @@ def test_reset_qconfig():
 def test_enable_and_disable_observer():
     net = init_qat_net()
     enable_observer(net)
-    assert net.quant.act_observer.enabled == True
-    assert net.linear.weight_observer.enabled == True
-    assert net.linear.act_observer.enabled == True
+    assert net.quant.act_observer.enabled is True
+    assert net.linear.weight_observer.enabled is True
+    assert net.linear.act_observer.enabled is True
     disable_observer(net)
-    assert net.quant.act_observer.enabled == False
-    assert net.linear.weight_observer.enabled == False
-    assert net.linear.act_observer.enabled == False
+    assert net.quant.act_observer.enabled is False
+    assert net.linear.weight_observer.enabled is False
+    assert net.linear.act_observer.enabled is False
 
 
 def test_enable_and_disable_fake_quant():
     net = init_qat_net()
     disable_fake_quant(net)
-    assert net.quant.act_fake_quant.enabled == False
-    assert net.linear.weight_fake_quant.enabled == False
-    assert net.linear.act_fake_quant.enabled == False
+    assert net.quant.act_fake_quant.enabled is False
+    assert net.linear.weight_fake_quant.enabled is False
+    assert net.linear.act_fake_quant.enabled is False
     enable_fake_quant(net)
-    assert net.quant.act_fake_quant.enabled == True
-    assert net.linear.weight_fake_quant.enabled == True
-    assert net.linear.act_fake_quant.enabled == True
+    assert net.quant.act_fake_quant.enabled is True
+    assert net.linear.weight_fake_quant.enabled is True
+    assert net.linear.act_fake_quant.enabled is True
 
 
 def init_observer(module, data):
@@ -144,7 +144,7 @@ def init_observer(module, data):
 
 def test_enable_and_disable_all():
     x = Tensor(np.random.randint(1, 10, size=(3, 3)).astype(np.float32))
-    net = Net()
+    net = FloatNet()
     y1 = net(x).numpy()
     net = quantize_qat(net, min_max_fakequant_qconfig)
 
@@ -162,7 +162,7 @@ def test_enable_and_disable_all():
 
 
 def test_quantize_qat():
-    net = Net()
+    net = FloatNet()
     qat_net = quantize_qat(net, inplace=False, qconfig=min_max_fakequant_qconfig)
     assert isinstance(qat_net.quant, QAT.QuantStub)
     assert isinstance(qat_net.linear, QAT.Linear)