diff --git a/frontend/src/components/header.tsx b/frontend/src/components/header.tsx
index f873707..f7e4e0d 100644
--- a/frontend/src/components/header.tsx
+++ b/frontend/src/components/header.tsx
@@ -28,20 +28,12 @@ import {
   DialogHeader,
   DialogTitle,
 } from "@/components/ui/dialog";
-import {
-  Select,
-  SelectContent,
-  SelectItem,
-  SelectTrigger,
-  SelectValue,
-} from "@/components/ui/select";
 import { toast } from "sonner";
 
 export function Header() {
   const { user, logout } = useAuth();
   const router = useRouter();
-  const { activeClassId, activeClassName, canSwitchClass, availableClasses, setActiveClassId } =
-    useActiveClass();
+  const { activeClassName } = useActiveClass();
   const { toggle } = useSidebar();
   const { unreadCount, notifications, markRead, markAllRead, refresh } = useNotifications();
   const [notifOpen, setNotifOpen] = useState(false);
@@ -52,9 +44,7 @@ export function Header() {
   const [newPassword, setNewPassword] = useState("");
   const [confirmPassword, setConfirmPassword] = useState("");
   const [passwordLoading, setPasswordLoading] = useState(false);
-  const classDescriptor = activeClassName
-    ? activeClassName.split(" ").slice(0, 2).join(" ")
-    : "香港大学中国商业学院";
+  const classDescriptor = activeClassName || "香港大学中国商业学院";
 
   const handleChangePassword = async (e: React.FormEvent) => {
     e.preventDefault();
@@ -99,32 +89,11 @@ export function Header() {
           <p className="text-[11px] uppercase tracking-[0.24em] text-[#94613e]">
             HKU ICB
           </p>
-          <h2 className="truncate text-lg font-semibold text-[#4a1f1a]">
+          <h2 className="text-lg font-semibold text-[#4a1f1a]">
             {classDescriptor}
           </h2>
         </div>
-        {canSwitchClass ? (
-          <Select
-            value={activeClassId ? String(activeClassId) : ""}
-            onValueChange={(v) => v && setActiveClassId(parseInt(v))}
-          >
-            <SelectTrigger className="w-56 border-[#d7c0a0] bg-white/75 shadow-none">
-              <SelectValue>
-                {activeClassId
-                  ? availableClasses.find((c) => c.id === activeClassId)?.name ||
-                    "选择班级"
-                  : "选择班级"}
-              </SelectValue>
-            </SelectTrigger>
-            <SelectContent>
-              {availableClasses.map((c) => (
-                <SelectItem key={c.id} value={String(c.id)}>
-                  {c.name} ({c.cohort_year})
-                </SelectItem>
-              ))}
-            </SelectContent>
-          </Select>
-        ) : activeClassName ? (
+        {activeClassName ? (
           <span className="text-sm text-[#6f4b38] md:hidden">
             当前班级：<span className="font-medium text-[#4a1f1a]">{activeClassName}</span>
           </span>
diff --git a/frontend/src/components/sidebar.tsx b/frontend/src/components/sidebar.tsx
index b598b4f..4e33eed 100644
--- a/frontend/src/components/sidebar.tsx
+++ b/frontend/src/components/sidebar.tsx
@@ -8,6 +8,13 @@ import { cn } from "@/lib/utils";
 import type { ClassPermission, UserRole } from "@/lib/types";
 import { useAuth } from "@/hooks/use-auth";
 import { hasClassPermission } from "@/lib/permissions";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
 
 const navItems = [
   { href: "/dashboard", label: "首页", icon: "M3 12l2-2m0 0l7-7 7 7M5 10v10a1 1 0 001 1h3m10-11l2 2m-2-2v10a1 1 0 01-1 1h-3m-6 0a1 1 0 001-1v-4a1 1 0 011-1h2a1 1 0 011 1v4a1 1 0 001 1m-6 0h6", moduleKey: undefined },
@@ -32,7 +39,14 @@ export function Sidebar() {
   const pathname = usePathname();
   const { isOpen, close } = useSidebar();
   const { user } = useAuth();
-  const { enabledModules, activeClassId } = useActiveClass();
+  const {
+    enabledModules,
+    activeClassId,
+    activeClassName,
+    canSwitchClass,
+    availableClasses,
+    setActiveClassId,
+  } = useActiveClass();
   const visibleAdminItems = user
     ? adminItems.filter((item) => {
         if (!item.roles.includes(user.role)) return false;
@@ -75,6 +89,39 @@ export function Sidebar() {
       <div className="border-b border-sidebar-border px-6 pb-6 pt-7">
         <h1 className="text-2xl font-semibold tracking-tight text-white">香港大学中国商业学院</h1>
         <p className="mt-1 text-sm text-white/65">HKU ICB</p>
+        {activeClassName && (
+          <div className="mt-5 rounded-2xl border border-white/10 bg-white/[0.06] p-4">
+            <p className="text-[11px] uppercase tracking-[0.22em] text-white/38">
+              当前班级
+            </p>
+            <p className="mt-2 text-sm font-medium leading-6 text-white">
+              {activeClassName}
+            </p>
+            {canSwitchClass && availableClasses.length > 1 && (
+              <div className="mt-3">
+                <Select
+                  value={activeClassId ? String(activeClassId) : ""}
+                  onValueChange={(value) => value && setActiveClassId(Number(value))}
+                >
+                  <SelectTrigger className="h-auto w-full rounded-xl border-white/12 bg-white/8 px-3 py-2 text-left text-sm text-white hover:bg-white/12">
+                    <SelectValue>
+                      {activeClassId
+                        ? availableClasses.find((item) => item.id === activeClassId)?.name ?? "切换班级"
+                        : "切换班级"}
+                    </SelectValue>
+                  </SelectTrigger>
+                  <SelectContent className="border-[#e2ccb0] bg-[#fffaf2]">
+                    {availableClasses.map((item) => (
+                      <SelectItem key={item.id} value={String(item.id)}>
+                        {item.name} ({item.cohort_year})
+                      </SelectItem>
+                    ))}
+                  </SelectContent>
+                </Select>
+              </div>
+            )}
+          </div>
+        )}
       </div>
 
       <nav className="flex-1 space-y-1 overflow-y-auto px-4 py-5">