diff --git a/frontend/components.d.ts b/frontend/components.d.ts
index 6d63c3e..4380d44 100644
--- a/frontend/components.d.ts
+++ b/frontend/components.d.ts
@@ -11,6 +11,7 @@ declare module 'vue' {
     AppMain: typeof import('./src/components/Layout/AppMain.vue')['default']
     AppSidebar: typeof import('./src/components/Layout/AppSidebar.vue')['default']
     AuditLogTable: typeof import('./src/components/AuditLogTable.vue')['default']
+    BusinessLineSwitcher: typeof import('./src/components/BusinessLineSwitcher.vue')['default']
     ElButton: typeof import('element-plus/es')['ElButton']
     ElIcon: typeof import('element-plus/es')['ElIcon']
     ElInput: typeof import('element-plus/es')['ElInput']
diff --git a/frontend/src/components/BusinessLineSwitcher.vue b/frontend/src/components/BusinessLineSwitcher.vue
new file mode 100644
index 0000000..c13e03e
--- /dev/null
+++ b/frontend/src/components/BusinessLineSwitcher.vue
@@ -0,0 +1,230 @@
+<template>
+  <div class="bl-switch" ref="switchRef">
+    <div class="bl-trigger" @click="toggleMenu">
+      <div
+        class="bl-ic"
+        :style="{ background: currentBL?.iconBg, color: currentBL?.iconColor }"
+      >
+        {{ currentBL?.iconText }}
+      </div>
+      <span class="bl-name-trigger">{{ currentBL?.name || '未选择' }}</span>
+      <span class="bl-role" v-if="currentBL">{{ currentBL.role }} · 授权 {{ authCount }} 子系统</span>
+      <span class="caret">▼</span>
+    </div>
+    <Transition name="bl-menu">
+      <div class="bl-menu" v-show="menuVisible">
+        <div class="bl-menu-label">切换业务线（仅展示被授权范围）</div>
+        <div
+          v-for="bl in businessLines"
+          :key="bl.id"
+          class="bl-opt"
+          :class="{ sel: bl.id === currentBL?.id, locked: !bl.authorized }"
+          @click="handleSelect(bl)"
+        >
+          <div
+            class="bl-ic"
+            :style="{ background: bl.iconBg, color: bl.iconColor }"
+          >
+            {{ bl.iconText }}
+          </div>
+          <div>
+            <div class="bl-name">{{ bl.name }}</div>
+            <div class="bl-sub">{{ bl.ou }} · {{ bl.role }}</div>
+          </div>
+          <span v-if="bl.authorized" class="bl-check">✓</span>
+          <span v-else class="bl-lock">🔒 无权限</span>
+        </div>
+      </div>
+    </Transition>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, computed, onMounted, onUnmounted } from 'vue'
+import { ElMessage } from 'element-plus'
+import { useBusinessLineStore, type BusinessLine } from '@/stores/businessLine'
+
+const blStore = useBusinessLineStore()
+
+const businessLines = computed(() => blStore.businessLines)
+const currentBL = computed(() => blStore.currentBL)
+const authCount = computed(() => blStore.authorizedBLs.length)
+
+const menuVisible = ref(false)
+const switchRef = ref<HTMLElement | null>(null)
+
+function toggleMenu() {
+  menuVisible.value = !menuVisible.value
+}
+
+function handleSelect(bl: BusinessLine) {
+  if (!bl.authorized) return
+  blStore.switchBL(bl.id)
+  menuVisible.value = false
+  ElMessage.success(`已切换业务线：${bl.name}（资源与告警按授权范围过滤）`)
+}
+
+function onClickOutside(e: MouseEvent) {
+  if (switchRef.value && !switchRef.value.contains(e.target as Node)) {
+    menuVisible.value = false
+  }
+}
+
+onMounted(() => {
+  document.addEventListener('click', onClickOutside)
+})
+
+onUnmounted(() => {
+  document.removeEventListener('click', onClickOutside)
+})
+</script>
+
+<style scoped>
+.bl-switch {
+  position: relative;
+}
+
+.bl-trigger {
+  display: flex;
+  align-items: center;
+  gap: 9px;
+  background: var(--bg-panel-2);
+  border: 1px solid var(--line);
+  border-radius: 8px;
+  padding: 6px 12px;
+  color: var(--text-hi);
+  font-size: 12.5px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: border-color 0.2s;
+}
+
+.bl-trigger:hover {
+  border-color: var(--accent);
+}
+
+.bl-trigger .bl-ic {
+  width: 20px;
+  height: 20px;
+  border-radius: 5px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-family: var(--mono);
+  font-size: 10px;
+  font-weight: 600;
+}
+
+.bl-trigger .caret {
+  color: var(--text-dim);
+  font-size: 10px;
+  margin-left: 2px;
+}
+
+.bl-trigger .bl-role {
+  font-family: var(--mono);
+  font-size: 10px;
+  color: var(--text-dim);
+}
+
+.bl-name-trigger {
+  font-size: 12.5px;
+}
+
+.bl-menu {
+  position: absolute;
+  top: 44px;
+  left: 0;
+  width: 280px;
+  z-index: 60;
+  background: var(--bg-panel);
+  border: 1px solid var(--line);
+  border-radius: 10px;
+  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.18);
+  padding: 6px;
+}
+
+.bl-menu-label {
+  font-size: 10px;
+  color: var(--text-dim);
+  text-transform: uppercase;
+  letter-spacing: 1px;
+  padding: 8px 10px 4px;
+}
+
+.bl-opt {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 9px 10px;
+  border-radius: 7px;
+  cursor: pointer;
+  transition: background 0.15s;
+}
+
+.bl-opt:hover {
+  background: var(--bg-panel-2);
+}
+
+.bl-opt.sel {
+  background: var(--accent-dim);
+}
+
+.bl-opt .bl-ic {
+  width: 24px;
+  height: 24px;
+  border-radius: 6px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-family: var(--mono);
+  font-size: 11px;
+  font-weight: 600;
+}
+
+.bl-opt .bl-name {
+  font-size: 13px;
+  color: var(--text-hi);
+  font-weight: 500;
+}
+
+.bl-opt .bl-sub {
+  font-size: 10.5px;
+  color: var(--text-dim);
+  font-family: var(--mono);
+}
+
+.bl-opt .bl-check {
+  margin-left: auto;
+  color: var(--accent);
+  font-size: 13px;
+  opacity: 0;
+}
+
+.bl-opt.sel .bl-check {
+  opacity: 1;
+}
+
+.bl-opt.locked {
+  opacity: 0.45;
+  cursor: not-allowed;
+}
+
+.bl-opt.locked .bl-lock {
+  margin-left: auto;
+  color: var(--text-dim);
+  font-size: 11px;
+}
+
+/* 下拉动画 */
+.bl-menu-enter-active,
+.bl-menu-leave-active {
+  transition: opacity 0.15s ease, transform 0.15s ease;
+}
+
+.bl-menu-enter-from,
+.bl-menu-leave-to {
+  opacity: 0;
+  transform: translateY(-6px);
+}
+</style>
diff --git a/frontend/src/components/Layout/AppHeader.vue b/frontend/src/components/Layout/AppHeader.vue
index 3833271..41ca71d 100644
--- a/frontend/src/components/Layout/AppHeader.vue
+++ b/frontend/src/components/Layout/AppHeader.vue
@@ -5,6 +5,7 @@
       xinfra <span class="sub">统一基础设施平台</span>
     </div>
     <span class="env-pill">● 生产环境</span>
+    <BusinessLineSwitcher />
     <div class="spacer"></div>
     <div class="search-box">
       <el-icon><Search /></el-icon>
@@ -23,7 +24,7 @@
       <div class="avatar">{{ userInitial }}</div>
       <div>
         <div>{{ user?.display_name || '未登录' }}</div>
-        <div class="ldap-tag">LDAP · {{ user?.business_line || '' }}业务线</div>
+        <div class="ldap-tag">LDAP · {{ user?.business_line || '' }}</div>
       </div>
       <el-button class="logout-button" text @click="handleLogout">退出</el-button>
     </div>
@@ -36,6 +37,7 @@ import { useAuthStore } from '@/stores/auth'
 import { useTheme } from '@/composables/useTheme'
 import { useAuth } from '@/composables/useAuth'
 import { Moon, Sunny } from '@element-plus/icons-vue'
+import BusinessLineSwitcher from '@/components/BusinessLineSwitcher.vue'
 
 const authStore = useAuthStore()
 const { logout } = useAuth()
diff --git a/frontend/src/stores/businessLine.ts b/frontend/src/stores/businessLine.ts
new file mode 100644
index 0000000..e7b69ab
--- /dev/null
+++ b/frontend/src/stores/businessLine.ts
@@ -0,0 +1,107 @@
+import { defineStore } from 'pinia'
+import { ref, computed } from 'vue'
+
+export interface BusinessLine {
+  id: string
+  name: string
+  ou: string
+  role: string
+  iconText: string
+  iconBg: string
+  iconColor: string
+  authorized: boolean
+}
+
+const STORAGE_KEY = 'xinfra-current-bl'
+
+// TODO: 替换为真实 API 调用
+const MOCK_BUSINESS_LINES: BusinessLine[] = [
+  {
+    id: 'las',
+    name: 'LAS 业务线',
+    ou: 'ou=las',
+    role: 'SRE',
+    iconText: 'LA',
+    iconBg: '#1A1430',
+    iconColor: '#C9A6FF',
+    authorized: true,
+  },
+  {
+    id: 'kodo',
+    name: 'Kodo 业务线',
+    ou: 'ou=kodo',
+    role: '研发',
+    iconText: 'KO',
+    iconBg: '#0E1C2C',
+    iconColor: '#8EC8FF',
+    authorized: true,
+  },
+  {
+    id: 'lingxi',
+    name: '灵矽 业务线',
+    ou: 'ou=lingxi',
+    role: '未授权',
+    iconText: 'LX',
+    iconBg: '#241B0A',
+    iconColor: '#FFC97A',
+    authorized: false,
+  },
+  {
+    id: 'ltoken',
+    name: 'LTOKEN 业务线',
+    ou: 'ou=ltoken',
+    role: '研发',
+    iconText: 'LT',
+    iconBg: '#1A2A1A',
+    iconColor: '#A6FFB0',
+    authorized: true,
+  },
+  {
+    id: 'maas',
+    name: 'MAAS 业务线',
+    ou: 'ou=maas',
+    role: '未授权',
+    iconText: 'MA',
+    iconBg: '#2A1A2A',
+    iconColor: '#FFB0E0',
+    authorized: false,
+  },
+]
+
+function loadSavedBL(): BusinessLine | null {
+  try {
+    const saved = localStorage.getItem(STORAGE_KEY)
+    if (saved) return JSON.parse(saved)
+  } catch {
+    // ignore
+  }
+  return null
+}
+
+export const useBusinessLineStore = defineStore('businessLine', () => {
+  const businessLines = ref<BusinessLine[]>(MOCK_BUSINESS_LINES)
+  const currentBL = ref<BusinessLine | null>(loadSavedBL())
+
+  // 默认选中第一个已授权的业务线
+  if (!currentBL.value) {
+    currentBL.value = businessLines.value.find((bl) => bl.authorized) || null
+  }
+
+  const authorizedBLs = computed(() =>
+    businessLines.value.filter((bl) => bl.authorized),
+  )
+
+  function switchBL(id: string) {
+    const bl = businessLines.value.find((b) => b.id === id)
+    if (!bl || !bl.authorized) return
+    currentBL.value = bl
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(bl))
+  }
+
+  return {
+    businessLines,
+    currentBL,
+    authorizedBLs,
+    switchBL,
+  }
+})