diff --git a/apps/common/serializers/fields.py b/apps/common/serializers/fields.py
index 84d4d5927..514a96fd0 100644
--- a/apps/common/serializers/fields.py
+++ b/apps/common/serializers/fields.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 #
+import phonenumbers
 from django.core.exceptions import ObjectDoesNotExist
 from django.utils.translation import gettext_lazy as _
 from rest_framework import serializers
@@ -17,6 +18,7 @@ __all__ = [
     "BitChoicesField",
     "TreeChoicesField",
     "LabeledMultipleChoiceField",
+    "PhoneField",
 ]
 
 
@@ -201,3 +203,11 @@ class BitChoicesField(TreeChoicesField):
         value = self.to_internal_value(data)
         self.run_validators(value)
         return value
+
+
+class PhoneField(serializers.CharField):
+    def to_representation(self, value):
+        if value:
+            phone = phonenumbers.parse(value, 'CN')
+            value = {'code': '+%s' % phone.country_code, 'phone': phone.national_number}
+        return value
diff --git a/apps/users/serializers/user.py b/apps/users/serializers/user.py
index 5d239820c..e21aab06b 100644
--- a/apps/users/serializers/user.py
+++ b/apps/users/serializers/user.py
@@ -8,7 +8,9 @@ from django.utils.translation import ugettext_lazy as _
 from rest_framework import serializers
 
 from common.serializers import CommonBulkSerializerMixin
-from common.serializers.fields import EncryptedField, ObjectRelatedField, LabeledChoiceField
+from common.serializers.fields import (
+    EncryptedField, ObjectRelatedField, LabeledChoiceField, PhoneField
+)
 from common.utils import pretty_string, get_logger
 from common.validators import PhoneValidator
 from rbac.builtin import BuiltinRole
@@ -103,6 +105,9 @@ class UserSerializer(RolesSerializerMixin, CommonBulkSerializerMixin, serializer
         label=_("Password"), required=False, allow_blank=True,
         allow_null=True, max_length=1024,
     )
+    phone = PhoneField(
+        validators=[PhoneValidator()], required=False, allow_null=True, label=_("Phone")
+    )
     custom_m2m_fields = {
         "system_roles": [BuiltinRole.system_user],
         "org_roles": [BuiltinRole.org_user],
@@ -169,7 +174,6 @@ class UserSerializer(RolesSerializerMixin, CommonBulkSerializerMixin, serializer
             "created_by": {"read_only": True, "allow_blank": True},
             "role": {"default": "User"},
             "is_otp_secret_key_bound": {"label": _("Is OTP bound")},
-            "phone": {"validators": [PhoneValidator()]},
             'mfa_level': {'label': _("MFA level")},
         }
 
@@ -224,14 +228,6 @@ class UserSerializer(RolesSerializerMixin, CommonBulkSerializerMixin, serializer
         attrs.pop("password_strategy", None)
         return attrs
 
-    def to_representation(self, instance):
-        data = super().to_representation(instance)
-        phone = phonenumbers.parse(data['phone'], 'CN')
-        data['phone'] = {
-            'code': '+%s' % phone.country_code, 'phone': phone.national_number
-        }
-        return data
-
     def save_and_set_custom_m2m_fields(self, validated_data, save_handler, created):
         m2m_values = {}
         for f, default_roles in self.custom_m2m_fields.items():