diff --git a/include/serial_AT.hpp b/include/serial_AT.hpp
index 9d3cd20..016f84a 100644
--- a/include/serial_AT.hpp
+++ b/include/serial_AT.hpp
@@ -2,6 +2,11 @@
 
 #include "serial_port.h"
 
+// 全局 IMEI（读取成功后写入）
+extern std::string IMEI;
+
+// 初始化 AT 串口（启动线程）
 void init_serial_at(const std::string& device, int baudrate);
 
-extern std::string IMEI;
+// 停止 AT 串口（停止线程，join）
+void stop_serial_at();
diff --git a/src/main.cpp b/src/main.cpp
index 8ad97fc..5c3446c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -86,6 +86,8 @@ int main()
     // 停止 RecordManager 自动扫描线程
     if (g_record_manager) g_record_manager->stopAutoScan();
 
+    stop_serial_at();
+
     RTMPManager::stop_all();
 
     if (mqtt_thread.joinable())
diff --git a/src/serial_AT.cpp b/src/serial_AT.cpp
index 7213a84..8430a62 100644
--- a/src/serial_AT.cpp
+++ b/src/serial_AT.cpp
@@ -1,13 +1,20 @@
 #include "serial_AT.hpp"
 
 #include <algorithm>
+#include <atomic>
 #include <chrono>
 #include <mutex>
 #include <sstream>
 #include <thread>
 
+#include "logger.hpp"
+#include "serial_port.h"
+
 // ================== 全局 IMEI ==================
-std::string IMEI;  // 一般 15 位
+std::string IMEI;
+
+// ================== 运行控制 ==================
+static std::atomic<bool> serial_at_running{false};
 
 // ================== AT 任务结构 ==================
 struct AtTask
@@ -28,7 +35,9 @@ static std::vector<AtTask> at_tasks = {{"AT+GSN", 3, 0, {}}};
 // ================== 发送线程 ==================
 static void serial_at_send_loop()
 {
-    while (true)
+    LOG_INFO("[serial_at] Sender thread started");
+
+    while (serial_at_running.load(std::memory_order_relaxed))
     {
         if (!serial_at || !serial_at->is_open())
         {
@@ -37,32 +46,36 @@ static void serial_at_send_loop()
         }
 
         auto now = std::chrono::steady_clock::now();
-        std::lock_guard<std::mutex> lock(at_tasks_mutex);
 
-        for (auto it = at_tasks.begin(); it != at_tasks.end();)
         {
-            auto& task = *it;
+            std::lock_guard<std::mutex> lock(at_tasks_mutex);
 
-            if (task.sent_count >= task.max_retries)
+            for (auto it = at_tasks.begin(); it != at_tasks.end();)
             {
-                // 达到最大重试次数，直接移除
-                it = at_tasks.erase(it);
-                continue;
-            }
+                auto& task = *it;
 
-            if (task.last_sent.time_since_epoch().count() == 0 ||
-                std::chrono::duration_cast<std::chrono::seconds>(now - task.last_sent).count() >= 5)
-            {
-                serial_at->send_data(task.cmd + "\r\n");
-                task.sent_count++;
-                task.last_sent = now;
-            }
+                if (task.sent_count >= task.max_retries)
+                {
+                    it = at_tasks.erase(it);
+                    continue;
+                }
 
-            ++it;
+                if (task.last_sent.time_since_epoch().count() == 0 ||
+                    std::chrono::duration_cast<std::chrono::seconds>(now - task.last_sent).count() >= 5)
+                {
+                    serial_at->send_data(task.cmd + "\r\n");
+                    task.sent_count++;
+                    task.last_sent = now;
+                }
+
+                ++it;
+            }
         }
 
         std::this_thread::sleep_for(std::chrono::seconds(1));
     }
+
+    LOG_INFO("[serial_at] Sender thread exiting");
 }
 
 // ================== 接收处理 ==================
@@ -77,13 +90,13 @@ static void handle_serial_at_data(const std::string& data)
         line.erase(0, line.find_first_not_of(" \t\r\n"));
         line.erase(line.find_last_not_of(" \t\r\n") + 1);
 
-        // IMEI：14~17 位纯数字（不同模组略有差异）
+        // IMEI：14~17 位纯数字
         if (line.size() >= 14 && line.size() <= 17 && std::all_of(line.begin(), line.end(), ::isdigit))
         {
             IMEI = line;
             LOG_INFO("[serial_at] IMEI = " + IMEI);
 
-            // 成功后清空任务，不再发送 AT
+            // 成功后清空任务，不再发送
             std::lock_guard<std::mutex> lock(at_tasks_mutex);
             at_tasks.clear();
             return;
@@ -91,14 +104,44 @@ static void handle_serial_at_data(const std::string& data)
     }
 }
 
-// ================== 初始化接口 ==================
+// ================== 初始化 ==================
 void init_serial_at(const std::string& device, int baudrate)
 {
-    serial_at = std::make_unique<SerialPort>("serial_at", device, baudrate, 5);
+    if (serial_at_running.load())
+    {
+        LOG_WARN("[serial_at] Already running");
+        return;
+    }
 
+    serial_at_running.store(true, std::memory_order_relaxed);
+
+    serial_at = std::make_unique<SerialPort>("serial_at", device, baudrate, 5);
     serial_at->set_receive_callback(handle_serial_at_data);
     serial_at->start();
 
     serial_at_sender = std::thread(serial_at_send_loop);
-    serial_at_sender.detach();
+}
+
+// ================== 停止 ==================
+void stop_serial_at()
+{
+    if (!serial_at_running.load()) return;
+
+    LOG_INFO("[serial_at] Stopping...");
+
+    serial_at_running.store(false, std::memory_order_relaxed);
+
+    if (serial_at)
+    {
+        serial_at->stop();  // 关闭串口，解除阻塞
+    }
+
+    if (serial_at_sender.joinable())
+    {
+        serial_at_sender.join();
+    }
+
+    serial_at.reset();
+
+    LOG_INFO("[serial_at] Stopped cleanly");
 }