diff --git a/apis/admin/user.api b/apis/admin/user.api
index 3f4ba90..8d01bda 100644
--- a/apis/admin/user.api
+++ b/apis/admin/user.api
@@ -51,7 +51,7 @@ type (
 		RefererId          *int64  `json:"referer_id"`
 		Enable             *bool   `json:"enable"`
 		IsAdmin            *bool   `json:"is_admin"`
-		Remark             string  `json:"remark"`
+		Remark             *string `json:"remark"`
 	}
 	UpdateUserNotifySettingRequest {
 		UserId                int64 `json:"user_id" validate:"required"`
diff --git a/internal/logic/admin/user/updateUserBasicInfoLogic.go b/internal/logic/admin/user/updateUserBasicInfoLogic.go
index d183604..3d5e504 100644
--- a/internal/logic/admin/user/updateUserBasicInfoLogic.go
+++ b/internal/logic/admin/user/updateUserBasicInfoLogic.go
@@ -101,7 +101,11 @@ func (l *UpdateUserBasicInfoLogic) UpdateUserBasicInfo(req *types.UpdateUserBasi
 		}
 
 		if req.Commission != nil && *req.Commission != userInfo.Commission {
-			if isWithdrawalScene(req.Remark) {
+			remark := ""
+			if req.Remark != nil {
+				remark = *req.Remark
+			}
+			if isWithdrawalScene(remark) {
 				logWithdrawalGuard(l.Logger, userInfo.Id)
 				return errors.Wrapf(xerr.NewErrCode(xerr.InvalidAccess), "commission overwrite is blocked in withdrawal scene")
 			}
@@ -129,8 +133,8 @@ func (l *UpdateUserBasicInfoLogic) UpdateUserBasicInfo(req *types.UpdateUserBasi
 		if req.IsAdmin != nil {
 			userInfo.IsAdmin = req.IsAdmin
 		}
-		if req.Remark != "" {
-			userInfo.Remark = req.Remark
+		if req.Remark != nil {
+			userInfo.Remark = *req.Remark
 		}
 		if req.OnlyFirstPurchase != nil {
 			userInfo.OnlyFirstPurchase = req.OnlyFirstPurchase
diff --git a/internal/types/types.go b/internal/types/types.go
index 8c5787f..c025ed9 100644
--- a/internal/types/types.go
+++ b/internal/types/types.go
@@ -3236,7 +3236,7 @@ type UpdateUserBasiceInfoRequest struct {
 	RefererId          *int64  `json:"referer_id"`
 	Enable             *bool   `json:"enable"`
 	IsAdmin            *bool   `json:"is_admin"`
-	Remark             string  `json:"remark"`
+	Remark             *string `json:"remark"`
 }
 
 type UpdateUserNotifyRequest struct {
diff --git a/internal/types/types_test.go b/internal/types/types_test.go
new file mode 100644
index 0000000..d5b9d10
--- /dev/null
+++ b/internal/types/types_test.go
@@ -0,0 +1,33 @@
+package types
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestUpdateUserBasiceInfoRequestDistinguishesOmittedAndEmptyRemark(t *testing.T) {
+	var omitted UpdateUserBasiceInfoRequest
+	if err := json.Unmarshal([]byte(`{"user_id":1001}`), &omitted); err != nil {
+		t.Fatalf("unmarshal omitted remark: %v", err)
+	}
+	if omitted.Remark != nil {
+		t.Fatalf("omitted remark should stay nil, got %q", *omitted.Remark)
+	}
+	if omitted.RefererId != nil {
+		t.Fatalf("omitted referer_id should stay nil, got %d", *omitted.RefererId)
+	}
+	if omitted.Balance != nil || omitted.GiftAmount != nil || omitted.Commission != nil {
+		t.Fatalf("omitted money fields should stay nil, got balance=%v gift=%v commission=%v", omitted.Balance, omitted.GiftAmount, omitted.Commission)
+	}
+
+	var cleared UpdateUserBasiceInfoRequest
+	if err := json.Unmarshal([]byte(`{"user_id":1001,"remark":""}`), &cleared); err != nil {
+		t.Fatalf("unmarshal empty remark: %v", err)
+	}
+	if cleared.Remark == nil {
+		t.Fatal("explicit empty remark should be present")
+	}
+	if *cleared.Remark != "" {
+		t.Fatalf("explicit empty remark should decode to empty string, got %q", *cleared.Remark)
+	}
+}