diff --git a/imperative/python/megengine/core/tensor/dtype.py b/imperative/python/megengine/core/tensor/dtype.py
index ea9eb358564c4904edcb2916d140e922ab88f306..ba3d569596d3c1377a489acd9ac5306d5ff7e1b2 100644
--- a/imperative/python/megengine/core/tensor/dtype.py
+++ b/imperative/python/megengine/core/tensor/dtype.py
@@ -146,6 +146,13 @@ def create_quantized_dtype(
     else:
         # Don't trick to combine with is_unsigned. Metadata should not contain
         # invalid field to keep consistent with c dtype.
+        if zp is not None:
+            raise ValueError(
+                "'{}' only supports symmetric quantization, "
+                "zero_point should be None, but actually got '{}'".format(
+                    dtype_meta.name, zp
+                )
+            )
         return np.dtype(
             dtype_meta.np_dtype_str,
             metadata={"mgb_dtype": {"name": dtype_meta.cname, "scale": float(scale)}},
diff --git a/imperative/python/megengine/quantization/utils.py b/imperative/python/megengine/quantization/utils.py
index 00699d3fba3de85d414bc80fae23dd759d53fc76..216c2172a99ac6f3344a863a7dd5215252cf5a69 100644
--- a/imperative/python/megengine/quantization/utils.py
+++ b/imperative/python/megengine/quantization/utils.py
@@ -210,6 +210,9 @@ def fake_quant_bias(bias: Tensor, inp: Tensor, w_qat: Tensor) -> Tensor:
         if inp_params.scale is None or w_params.scale is None:
             return b_qat
 
+        if inp_params.mode != QuantMode.SYMMERTIC:
+            return b_qat
+
         # TODO: support different mode
         if inp_params.mode != w_params.mode:
             return b_qat