diff --git a/internal/web/ui.go b/internal/web/ui.go
index 1dba4b6..ef0adb3 100644
--- a/internal/web/ui.go
+++ b/internal/web/ui.go
@@ -744,6 +744,7 @@ func (u *UI) Routes() (chi.Router, error) {
     r.Post("/wizard/apply", u.actionWizardApply)
     r.Post("/wizard/create-source", u.actionWizardCreateSource)
     r.Get("/devices", u.pageDevices)
+    r.Post("/devices/cleanup-offline", u.actionDevicesCleanupOffline)
     r.Get("/devices/{id}/control", u.pageDeviceControl)
     r.Get("/plans", u.redirectPlansToSceneTemplates)
     r.Get("/plans/{name}", u.redirectPlanToSceneTemplate)
@@ -1572,6 +1573,32 @@ func (u *UI) pageDevices(w http.ResponseWriter, r *http.Request) {
     u.render(w, r, "devices", u.deviceOverviewPageData(r, nil, ""))
 }
 
+func (u *UI) actionDevicesCleanupOffline(w http.ResponseWriter, r *http.Request) {
+    u.ensureDevicesLoaded()
+    devices := u.registry.GetDevices()
+    deleted := 0
+    for _, dev := range devices {
+        if dev == nil || dev.Online || dev.DeviceID == "" {
+            continue
+        }
+        // Delete related data from DB
+        if strings.TrimSpace(u.dbPath) != "" {
+            if store, err := storage.OpenSQLite(u.dbPath); err == nil {
+                db := store.DB()
+                db.Exec("DELETE FROM device_assignments WHERE device_id = ?", dev.DeviceID)
+                db.Exec("DELETE FROM recognition_units WHERE scene_template_name IN (SELECT profile_name FROM device_assignments WHERE device_id = ?)", dev.DeviceID)
+                db.Exec("DELETE FROM device_config_state WHERE device_id = ?", dev.DeviceID)
+                db.Exec("DELETE FROM device_features WHERE device_id = ?", dev.DeviceID)
+                db.Exec("DELETE FROM config_versions WHERE device_id = ?", dev.DeviceID)
+                db.Exec("DELETE FROM devices WHERE device_id = ?", dev.DeviceID)
+                store.Close()
+            }
+        }
+        deleted++
+    }
+    http.Redirect(w, r, "/devices?msg="+urlQueryEscape(fmt.Sprintf("已清理 %d 台离线设备", deleted)), http.StatusFound)
+}
+
 func (u *UI) pageDeviceAdd(w http.ResponseWriter, r *http.Request) {
     u.render(w, r, "device_add", PageData{Title: "新增设备"})
 }
diff --git a/internal/web/ui/templates/devices.html b/internal/web/ui/templates/devices.html
index e4fdf13..01fbdfb 100644
--- a/internal/web/ui/templates/devices.html
+++ b/internal/web/ui/templates/devices.html
@@ -29,6 +29,11 @@
     </div>
     <div class="table-tools">
       <input id="device-filter" placeholder="搜索设备名、ID 或 IP" />
+      {{if gt .OfflineCount 0}}
+      <form method="post" action="/devices/cleanup-offline" style="display:inline" onsubmit="return confirm('确认清理全部 ' + {{.OfflineCount}} + ' 台离线设备及其相关数据？此操作不可恢复。')">
+        <button type="submit" class="btn danger">清理离线设备 ({{.OfflineCount}})</button>
+      </form>
+      {{end}}
     </div>
   </div>
 
diff --git a/safesightd-linux-arm64 b/safesightd-linux-arm64
index 454182b..74abb66 100644
Binary files a/safesightd-linux-arm64 and b/safesightd-linux-arm64 differ