diff --git a/backend/internal/handler/admin/group_handler.go b/backend/internal/handler/admin/group_handler.go
index 5be66768..4725c3d1 100644
--- a/backend/internal/handler/admin/group_handler.go
+++ b/backend/internal/handler/admin/group_handler.go
@@ -1,6 +1,9 @@
 package admin
 
 import (
+	"bytes"
+	"encoding/json"
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -16,6 +19,55 @@ type GroupHandler struct {
 	adminService service.AdminService
 }
 
+type optionalLimitField struct {
+	set   bool
+	value *float64
+}
+
+func (f *optionalLimitField) UnmarshalJSON(data []byte) error {
+	f.set = true
+
+	trimmed := bytes.TrimSpace(data)
+	if bytes.Equal(trimmed, []byte("null")) {
+		f.value = nil
+		return nil
+	}
+
+	var number float64
+	if err := json.Unmarshal(trimmed, &number); err == nil {
+		f.value = &number
+		return nil
+	}
+
+	var text string
+	if err := json.Unmarshal(trimmed, &text); err == nil {
+		text = strings.TrimSpace(text)
+		if text == "" {
+			f.value = nil
+			return nil
+		}
+		number, err = strconv.ParseFloat(text, 64)
+		if err != nil {
+			return fmt.Errorf("invalid numeric limit value %q: %w", text, err)
+		}
+		f.value = &number
+		return nil
+	}
+
+	return fmt.Errorf("invalid limit value: %s", string(trimmed))
+}
+
+func (f optionalLimitField) ToServiceInput() *float64 {
+	if !f.set {
+		return nil
+	}
+	if f.value != nil {
+		return f.value
+	}
+	zero := 0.0
+	return &zero
+}
+
 // NewGroupHandler creates a new admin group handler
 func NewGroupHandler(adminService service.AdminService) *GroupHandler {
 	return &GroupHandler{
@@ -31,9 +83,9 @@ type CreateGroupRequest struct {
 	RateMultiplier   float64  `json:"rate_multiplier"`
 	IsExclusive      bool     `json:"is_exclusive"`
 	SubscriptionType string   `json:"subscription_type" binding:"omitempty,oneof=standard subscription"`
-	DailyLimitUSD    *float64 `json:"daily_limit_usd"`
-	WeeklyLimitUSD   *float64 `json:"weekly_limit_usd"`
-	MonthlyLimitUSD  *float64 `json:"monthly_limit_usd"`
+	DailyLimitUSD    optionalLimitField `json:"daily_limit_usd"`
+	WeeklyLimitUSD   optionalLimitField `json:"weekly_limit_usd"`
+	MonthlyLimitUSD  optionalLimitField `json:"monthly_limit_usd"`
 	// 图片生成计费配置（antigravity 和 gemini 平台使用，负数表示清除配置）
 	ImagePrice1K                    *float64 `json:"image_price_1k"`
 	ImagePrice2K                    *float64 `json:"image_price_2k"`
@@ -69,9 +121,9 @@ type UpdateGroupRequest struct {
 	IsExclusive      *bool    `json:"is_exclusive"`
 	Status           string   `json:"status" binding:"omitempty,oneof=active inactive"`
 	SubscriptionType string   `json:"subscription_type" binding:"omitempty,oneof=standard subscription"`
-	DailyLimitUSD    *float64 `json:"daily_limit_usd"`
-	WeeklyLimitUSD   *float64 `json:"weekly_limit_usd"`
-	MonthlyLimitUSD  *float64 `json:"monthly_limit_usd"`
+	DailyLimitUSD    optionalLimitField `json:"daily_limit_usd"`
+	WeeklyLimitUSD   optionalLimitField `json:"weekly_limit_usd"`
+	MonthlyLimitUSD  optionalLimitField `json:"monthly_limit_usd"`
 	// 图片生成计费配置（antigravity 和 gemini 平台使用，负数表示清除配置）
 	ImagePrice1K                    *float64 `json:"image_price_1k"`
 	ImagePrice2K                    *float64 `json:"image_price_2k"`
@@ -191,9 +243,9 @@ func (h *GroupHandler) Create(c *gin.Context) {
 		RateMultiplier:                  req.RateMultiplier,
 		IsExclusive:                     req.IsExclusive,
 		SubscriptionType:                req.SubscriptionType,
-		DailyLimitUSD:                   req.DailyLimitUSD,
-		WeeklyLimitUSD:                  req.WeeklyLimitUSD,
-		MonthlyLimitUSD:                 req.MonthlyLimitUSD,
+		DailyLimitUSD:                   req.DailyLimitUSD.ToServiceInput(),
+		WeeklyLimitUSD:                  req.WeeklyLimitUSD.ToServiceInput(),
+		MonthlyLimitUSD:                 req.MonthlyLimitUSD.ToServiceInput(),
 		ImagePrice1K:                    req.ImagePrice1K,
 		ImagePrice2K:                    req.ImagePrice2K,
 		ImagePrice4K:                    req.ImagePrice4K,
@@ -244,9 +296,9 @@ func (h *GroupHandler) Update(c *gin.Context) {
 		IsExclusive:                     req.IsExclusive,
 		Status:                          req.Status,
 		SubscriptionType:                req.SubscriptionType,
-		DailyLimitUSD:                   req.DailyLimitUSD,
-		WeeklyLimitUSD:                  req.WeeklyLimitUSD,
-		MonthlyLimitUSD:                 req.MonthlyLimitUSD,
+		DailyLimitUSD:                   req.DailyLimitUSD.ToServiceInput(),
+		WeeklyLimitUSD:                  req.WeeklyLimitUSD.ToServiceInput(),
+		MonthlyLimitUSD:                 req.MonthlyLimitUSD.ToServiceInput(),
 		ImagePrice1K:                    req.ImagePrice1K,
 		ImagePrice2K:                    req.ImagePrice2K,
 		ImagePrice4K:                    req.ImagePrice4K,
diff --git a/frontend/src/views/admin/GroupsView.vue b/frontend/src/views/admin/GroupsView.vue
index a78762d6..71fa7a20 100644
--- a/frontend/src/views/admin/GroupsView.vue
+++ b/frontend/src/views/admin/GroupsView.vue
@@ -2368,6 +2368,23 @@ const closeCreateModal = () => {
   createModelRoutingRules.value = []
 }
 
+const normalizeOptionalLimit = (value: number | string | null | undefined): number | null => {
+  if (value === null || value === undefined) {
+    return null
+  }
+
+  if (typeof value === 'string') {
+    const trimmed = value.trim()
+    if (!trimmed) {
+      return null
+    }
+    const parsed = Number(trimmed)
+    return Number.isFinite(parsed) && parsed > 0 ? parsed : null
+  }
+
+  return Number.isFinite(value) && value > 0 ? value : null
+}
+
 const handleCreateGroup = async () => {
   if (!createForm.name.trim()) {
     appStore.showError(t('admin.groups.nameRequired'))
@@ -2379,6 +2396,9 @@ const handleCreateGroup = async () => {
     const { sora_storage_quota_gb: createQuotaGb, ...createRest } = createForm
     const requestData = {
       ...createRest,
+      daily_limit_usd: normalizeOptionalLimit(createForm.daily_limit_usd as number | string | null),
+      weekly_limit_usd: normalizeOptionalLimit(createForm.weekly_limit_usd as number | string | null),
+      monthly_limit_usd: normalizeOptionalLimit(createForm.monthly_limit_usd as number | string | null),
       sora_storage_quota_bytes: createQuotaGb ? Math.round(createQuotaGb * 1024 * 1024 * 1024) : 0,
       model_routing: convertRoutingRulesToApiFormat(createModelRoutingRules.value)
     }
@@ -2457,6 +2477,9 @@ const handleUpdateGroup = async () => {
     const { sora_storage_quota_gb: editQuotaGb, ...editRest } = editForm
     const payload = {
       ...editRest,
+      daily_limit_usd: normalizeOptionalLimit(editForm.daily_limit_usd as number | string | null),
+      weekly_limit_usd: normalizeOptionalLimit(editForm.weekly_limit_usd as number | string | null),
+      monthly_limit_usd: normalizeOptionalLimit(editForm.monthly_limit_usd as number | string | null),
       sora_storage_quota_bytes: editQuotaGb ? Math.round(editQuotaGb * 1024 * 1024 * 1024) : 0,
       fallback_group_id: editForm.fallback_group_id === null ? 0 : editForm.fallback_group_id,
       fallback_group_id_on_invalid_request: