diff --git a/app/src/ui/main_window.cpp b/app/src/ui/main_window.cpp
index 73aac9a..234c61a 100644
--- a/app/src/ui/main_window.cpp
+++ b/app/src/ui/main_window.cpp
@@ -176,13 +176,7 @@ MainWindow::MainWindow(
     configureHmiEditor();
     configureLogicEditor();
     runtime_mode_service_.setPlcStatusChangedCallback(
-        [this]
-        {
-            QMetaObject::invokeMethod(
-                this,
-                [this] { updateModeUi(plcStatusText(runtime_mode_service_)); },
-                Qt::QueuedConnection);
-        });
+        [this] { schedulePlcStatusUpdate(); });
     hmi_editor_service_.ensureDefaultPage();
     logic_editor_service_.ensureDefaultLogic();
     refreshProjectUi();
@@ -581,7 +575,23 @@ void MainWindow::connectPlc()
 void MainWindow::disconnectPlc()
 {
     runtime_mode_service_.disconnectPlc();
-    updateModeUi(tr("PLC 已断开"));
+}
+
+void MainWindow::schedulePlcStatusUpdate()
+{
+    if (plc_status_update_pending_)
+    {
+        return;
+    }
+    plc_status_update_pending_ = true;
+    QMetaObject::invokeMethod(
+        this,
+        [this]
+        {
+            plc_status_update_pending_ = false;
+            updateModeUi(plcStatusText(runtime_mode_service_));
+        },
+        Qt::QueuedConnection);
 }
 
 // 根据控件ID加载控件属性到右侧属性面板
@@ -1126,8 +1136,13 @@ void MainWindow::updateModeUi(const QString &message)
     }
     updateSimulationUi(false);
     statusBar()->showMessage(message, 4000);
-    ui_->outputList->addItem(message);
-    ui_->outputList->scrollToBottom();
+    const bool duplicate = ui_->outputList->count() > 0
+        && ui_->outputList->item(ui_->outputList->count() - 1)->text() == message;
+    if (!duplicate)
+    {
+        ui_->outputList->addItem(message);
+        ui_->outputList->scrollToBottom();
+    }
 }
 
 void MainWindow::updateSimulationUi(bool report_fault)
diff --git a/app/src/ui/main_window.h b/app/src/ui/main_window.h
index 3d86cb5..de994af 100644
--- a/app/src/ui/main_window.h
+++ b/app/src/ui/main_window.h
@@ -101,6 +101,8 @@ private:
     void applySelectedLogicNodeProperties();
     void connectPlc();
     void disconnectPlc();
+    // 合并同一事件循环内的 PLC 状态通知，避免重复刷新和重复日志
+    void schedulePlcStatusUpdate();
     // 创建新的工程并刷新编辑界面
     void createNewProject();
     // 保存当前工程到已关联的路径
@@ -155,4 +157,5 @@ private:
     PlcSerialConfiguration plc_configuration_;
     std::string selected_control_id_;
     std::string selected_logic_node_id_;
+    bool plc_status_update_pending_ = false;
 };
diff --git a/app/tests/main_window_tests.cpp b/app/tests/main_window_tests.cpp
index 08aa837..a5b960d 100644
--- a/app/tests/main_window_tests.cpp
+++ b/app/tests/main_window_tests.cpp
@@ -1,3 +1,4 @@
+#include "domain/active_register_repository.h"
 #include "domain/project_storage.h"
 #include "domain/register_repository.h"
 #include "services/hmi_editor_service.h"
@@ -18,6 +19,7 @@
 #include <QDockWidget>
 #include <QLabel>
 #include <QLineEdit>
+#include <QListWidget>
 #include <QSpinBox>
 #include <QTimer>
 
@@ -42,6 +44,60 @@ public:
     }
 };
 
+class RepeatedStatusGateway final : public PlcCommunicationGateway
+{
+public:
+    PlcCommunicationResult connectDevice(
+        const PlcSerialConfiguration &) override
+    {
+        connection_state = PlcConnectionState::Connecting;
+        notifyStateChanged();
+        connection_state = PlcConnectionState::Connected;
+        notifyStateChanged();
+        notifyStateChanged();
+        return {true, {}};
+    }
+
+    void disconnectDevice() override
+    {
+        connection_state = PlcConnectionState::Disconnected;
+        notifyStateChanged();
+    }
+
+    void setPollAddresses(const std::vector<RegisterAddress> &) override {}
+    PlcConnectionState state() const override { return connection_state; }
+    bool initialReadCompleted() const override { return false; }
+    const std::string &lastError() const override { return last_error; }
+
+    void setCallbacks(
+        std::function<void()> state_callback,
+        std::function<void(bool)> initial_callback,
+        std::function<void()> cache_callback,
+        std::function<void(const std::string &)> error_callback) override
+    {
+        state_changed = std::move(state_callback);
+        initial_read_changed = std::move(initial_callback);
+        cache_updated = std::move(cache_callback);
+        error_reported = std::move(error_callback);
+    }
+
+private:
+    void notifyStateChanged()
+    {
+        if (state_changed)
+        {
+            state_changed();
+        }
+    }
+
+    PlcConnectionState connection_state = PlcConnectionState::Disconnected;
+    std::string last_error;
+    std::function<void()> state_changed;
+    std::function<void(bool)> initial_read_changed;
+    std::function<void()> cache_updated;
+    std::function<void(const std::string &)> error_reported;
+};
+
 void require(bool condition, const std::string &message)
 {
     if (!condition)
@@ -273,6 +329,48 @@ void testPlcConfigurationUsesDialog()
             "PLC configuration action must open the dedicated configuration dialog");
 }
 
+void testRepeatedPlcStatusNotificationsAreCoalesced()
+{
+    TestProjectStorage storage;
+    ProjectService project_service(storage);
+    HmiEditorService editor_service(project_service);
+    LogicEditorService logic_editor_service(project_service);
+    VirtualRegisterRepository virtual_repository;
+    VirtualRegisterRepository plc_repository;
+    ActiveRegisterRepository active_repository(virtual_repository);
+    HmiRuntimeService runtime_service(active_repository);
+    OfflineSimulationService simulation_service(virtual_repository);
+    RuntimeModeService mode_service(project_service, simulation_service);
+    RepeatedStatusGateway gateway;
+    mode_service.configurePlc(
+        gateway, active_repository, virtual_repository, plc_repository);
+    MainWindow window(
+        mode_service,
+        project_service,
+        editor_service,
+        logic_editor_service,
+        runtime_service);
+    QListWidget *output = requiredChild<QListWidget>(window, "outputList");
+    const int initial_count = output->count();
+
+    const PlcCommunicationResult result = mode_service.connectPlc(
+        {"COM3", 1, 9600, 8, 2, 1, 1000, 2, 200});
+    require(result.succeeded, "PLC connection setup must succeed");
+    QApplication::processEvents();
+
+    const QString expected = QStringLiteral("PLC 已连接，正在读取工程使用的 M/D 地址");
+    int matching_count = 0;
+    for (int index = initial_count; index < output->count(); ++index)
+    {
+        if (output->item(index)->text() == expected)
+        {
+            ++matching_count;
+        }
+    }
+    require(matching_count == 1,
+            "repeated PLC status callbacks must append one coalesced output message");
+}
+
 } // namespace
 
 int main(int argc, char *argv[])
@@ -285,6 +383,7 @@ int main(int argc, char *argv[])
     {
         testModeActionsControlEditingAvailability();
         testPlcConfigurationUsesDialog();
+        testRepeatedPlcStatusNotificationsAreCoalesced();
     }
     catch (const std::exception &error)
     {