diff --git a/backend/internal/handler/instance_group.go b/backend/internal/handler/instance_group.go
index 3e443a2..bcffce1 100644
--- a/backend/internal/handler/instance_group.go
+++ b/backend/internal/handler/instance_group.go
@@ -25,15 +25,55 @@ func GetInstanceGroup(c *gin.Context) {
 
 // POST /api/v1/instance-groups
 func CreateInstanceGroup(c *gin.Context) {
-	var group model.InstanceGroup
-	if err := c.ShouldBindJSON(&group); err != nil {
+	var input struct {
+		Name                string  `json:"name"`
+		Description         *string `json:"description"`
+		DBType              string  `json:"db_type"`
+		IsActive            *bool   `json:"is_active"`
+		ReadonlyInstanceIDs []int   `json:"readonly_instance_ids"`
+		WriteInstanceIDs    []int   `json:"write_instance_ids"`
+	}
+	if err := c.ShouldBindJSON(&input); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"detail": err.Error()})
 		return
 	}
+
+	desc := ""
+	if input.Description != nil {
+		desc = *input.Description
+	}
+	isActive := true
+	if input.IsActive != nil {
+		isActive = *input.IsActive
+	}
+	dbType := input.DBType
+	if dbType == "" {
+		dbType = "all"
+	}
+
+	group := model.InstanceGroup{
+		Name:        input.Name,
+		Description: &desc,
+		DBType:      dbType,
+		IsActive:    &isActive,
+	}
 	if err := model.DB.Create(&group).Error; err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"detail": err.Error()})
 		return
 	}
+
+	// Create instance members
+	for _, iid := range input.ReadonlyInstanceIDs {
+		model.DB.Create(&model.InstanceGroupMember{
+			GroupID: group.ID, InstanceID: iid, AccessType: "readonly",
+		})
+	}
+	for _, iid := range input.WriteInstanceIDs {
+		model.DB.Create(&model.InstanceGroupMember{
+			GroupID: group.ID, InstanceID: iid, AccessType: "write",
+		})
+	}
+
 	c.JSON(http.StatusCreated, enrichGroup(group))
 }
 
diff --git a/frontend/src/pages/InstanceGroupPage.tsx b/frontend/src/pages/InstanceGroupPage.tsx
index d27fd64..f88dd77 100644
--- a/frontend/src/pages/InstanceGroupPage.tsx
+++ b/frontend/src/pages/InstanceGroupPage.tsx
@@ -257,10 +257,13 @@ export default function InstanceGroupPage() {
     const close = () => { setShowCreateModal(false); setShowEditModal(false); resetForm(); };
     const submit = mode === 'create' ? handleCreate : handleEdit;
     return show ? (
-      <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
-        <div className="w-full max-w-3xl bg-[var(--dg-bg-primary)] rounded-xl p-6 shadow-2xl max-h-[90vh] overflow-y-auto" onClick={e => e.stopPropagation()}>
-          <h3 className="text-lg font-semibold mb-5">{mode === 'create' ? '新建权限策略' : '编辑权限策略'}</h3>
-          <div className="space-y-5">
+      <div className="fixed inset-0 z-[100] flex items-start justify-center pt-[5vh] bg-black/60 backdrop-blur-sm">
+        <div className="w-full max-w-3xl bg-[var(--dg-bg-primary)] rounded-xl shadow-2xl flex flex-col max-h-[90vh] border border-[var(--dg-border)]" onClick={e => e.stopPropagation()}>
+          <div className="flex items-center justify-between px-6 py-4 border-b border-[var(--dg-border)]">
+            <h3 className="text-lg font-semibold">{mode === 'create' ? '新建权限策略' : '编辑权限策略'}</h3>
+            <button onClick={close} className="p-1.5 rounded-lg hover:bg-[var(--dg-bg-hover)] text-[var(--dg-text-muted)] hover:text-[var(--dg-text-primary)] transition-colors"><X className="w-4 h-4" /></button>
+          </div>
+          <div className="overflow-y-auto px-6 py-5 space-y-5 flex-1">
             <div className="grid grid-cols-2 gap-4">
               <div>
                 <label className="block text-sm font-medium mb-1.5">策略名称 <span className="text-red-400">*</span></label>
@@ -293,8 +296,8 @@ export default function InstanceGroupPage() {
             </div>
 
             <div className="flex justify-end gap-3 pt-2">
-              <button onClick={close} className="px-4 py-2 text-sm text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)] transition-colors">取消</button>
-              <button onClick={submit} disabled={!formName.trim()} className="px-4 py-2 text-sm bg-blue-500 text-white rounded-lg hover:bg-blue-600 disabled:opacity-50 transition-colors">
+              <button onClick={close} className="px-4 py-2 text-sm text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)] transition-colors rounded-lg hover:bg-[var(--dg-bg-hover)]">取消</button>
+              <button onClick={submit} disabled={!formName.trim()} className="dg-btn dg-btn-primary disabled:opacity-50">
                 {mode === 'create' ? '创建' : '保存'}
               </button>
             </div>
@@ -438,9 +441,13 @@ export default function InstanceGroupPage() {
 
       {/* User Modal */}
       {showUserModal && (
-        <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
-          <div className="w-full max-w-md bg-[var(--dg-bg-primary)] rounded-xl p-6 shadow-2xl" onClick={e => e.stopPropagation()}>
-            <h3 className="text-lg font-semibold mb-4">关联用户</h3>
+        <div className="fixed inset-0 z-[100] flex items-start justify-center pt-[10vh] bg-black/60 backdrop-blur-sm">
+          <div className="w-full max-w-md bg-[var(--dg-bg-primary)] rounded-xl shadow-2xl border border-[var(--dg-border)]" onClick={e => e.stopPropagation()}>
+            <div className="flex items-center justify-between px-6 py-4 border-b border-[var(--dg-border)]">
+              <h3 className="text-lg font-semibold">关联用户</h3>
+              <button onClick={() => setShowUserModal(false)} className="p-1.5 rounded-lg hover:bg-[var(--dg-bg-hover)] text-[var(--dg-text-muted)] hover:text-[var(--dg-text-primary)] transition-colors"><X className="w-4 h-4" /></button>
+            </div>
+            <div className="px-6 py-4">
             <div className="relative mb-3">
               <Search className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-[var(--dg-text-muted)]" />
               <input value={userSearch} onChange={e => setUserSearch(e.target.value)} placeholder="搜索用户..." className="w-full pl-10 pr-4 py-2 bg-[var(--dg-bg-tertiary)] border border-[var(--dg-border)] rounded-lg text-sm focus:border-blue-400 focus:outline-none" />
@@ -456,9 +463,10 @@ export default function InstanceGroupPage() {
               ))}
             </div>
             <div className="flex justify-end gap-3">
-              <button onClick={() => setShowUserModal(false)} className="px-4 py-2 text-sm text-[var(--dg-text-secondary)]">取消</button>
-              <button onClick={handleAssignUsers} disabled={selectedUserIds.length === 0} className="px-4 py-2 text-sm bg-blue-500 text-white rounded-lg hover:bg-blue-600 disabled:opacity-50">确认 ({selectedUserIds.length})</button>
+              <button onClick={() => setShowUserModal(false)} className="px-4 py-2 text-sm text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)] transition-colors rounded-lg hover:bg-[var(--dg-bg-hover)]">取消</button>
+              <button onClick={handleAssignUsers} disabled={selectedUserIds.length === 0} className="dg-btn dg-btn-primary disabled:opacity-50">确认 ({selectedUserIds.length})</button>
             </div>
+            </div>{/* end px-6 py-4 */}
           </div>
         </div>
       )}