diff --git a/tauri-app/src-tauri/src/lib.rs b/tauri-app/src-tauri/src/lib.rs
index 40099c0..0b86571 100644
--- a/tauri-app/src-tauri/src/lib.rs
+++ b/tauri-app/src-tauri/src/lib.rs
@@ -46,6 +46,71 @@ pub struct ApiResponse<T> {
     pub data: Option<T>,
 }
 
+// ============================================================
+// 视频缓存清理
+// ============================================================
+
+/// 清理 video_cache 目录
+///
+/// 策略：
+/// 1. 删除超过 30 天未修改的文件
+/// 2. 总容量超过 500MB 时，按修改时间删最旧文件直到 300MB
+fn clean_video_cache(app_data_dir: &std::path::Path) {
+    let cache_dir = app_data_dir.join("video_cache");
+    if !cache_dir.exists() {
+        return;
+    }
+
+    let max_age = std::time::Duration::from_secs(30 * 24 * 60 * 60);
+    let max_total_size: u64 = 500 * 1024 * 1024;
+    let target_size: u64 = 300 * 1024 * 1024;
+    let now = std::time::SystemTime::now();
+
+    let mut entries: Vec<(std::path::PathBuf, std::time::SystemTime, u64)> = Vec::new();
+    let mut total_size: u64 = 0;
+
+    let read_dir = match std::fs::read_dir(&cache_dir) {
+        Ok(d) => d,
+        Err(e) => {
+            eprintln!("[cache] 无法读取缓存目录: {}", e);
+            return;
+        }
+    };
+
+    for entry in read_dir.flatten() {
+        let Ok(metadata) = entry.metadata() else { continue };
+        if !metadata.is_file() { continue; }
+        let mtime = metadata.modified().unwrap_or(now);
+        let size = metadata.len();
+        total_size += size;
+        entries.push((entry.path(), mtime, size));
+    }
+
+    // 1. 删除超过 30 天的文件
+    let mut deleted_size: u64 = 0;
+    for (path, mtime, size) in &entries {
+        if now.duration_since(*mtime).unwrap_or_default() > max_age {
+            if std::fs::remove_file(path).is_ok() {
+                deleted_size += size;
+            }
+        }
+    }
+
+    // 2. 容量超限，删最旧的
+    let remaining_size = total_size.saturating_sub(deleted_size);
+    if remaining_size > max_total_size {
+        let mut sorted = entries;
+        sorted.sort_by_key(|(_, mtime, _)| *mtime);
+        let mut to_free = remaining_size.saturating_sub(target_size);
+        for (path, _, size) in sorted {
+            if to_free == 0 { break; }
+            if path.exists() && std::fs::remove_file(&path).is_ok() {
+                to_free = to_free.saturating_sub(size);
+            }
+        }
+    }
+}
+
 // ============================================================
 // 应用入口
 // ============================================================
@@ -69,7 +134,9 @@ pub fn run() {
         .setup(|app| {
             // 初始化应用数据目录（所有业务数据的根目录）
             if let Ok(app_data_dir) = app.path().app_local_data_dir() {
-                crate::storage::init_app_data_dir(app_data_dir);
+                crate::storage::init_app_data_dir(app_data_dir.clone());
+                // 后台清理过期视频缓存，不阻塞首屏
+                std::thread::spawn(move || clean_video_cache(&app_data_dir));
             }
 
             // 窗口初始 visible=false，setup 阶段先显示窗口