diff --git a/src/device/DeviceManager.cpp b/src/device/DeviceManager.cpp
index bd186fd..077f6cb 100644
--- a/src/device/DeviceManager.cpp
+++ b/src/device/DeviceManager.cpp
@@ -85,6 +85,12 @@ QString getFullScanJson(QObject* obj)
 
 void DeviceManager::initDevice()
 {
+    if(!AppGlobalValues::DBconnected().toBool())
+    {
+        emitErrorCallback("Fail to connect to DB!Reboot device to try!");
+        emit initializeFinished();
+        return;
+    }
     dmsmq_init();
 
     // empty scan
diff --git a/src/main.cpp b/src/main.cpp
index c47438f..f74317e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -91,7 +91,11 @@ int main(int argc, char* argv[])
     int ret = 0;
     KeyboardManager::getInstance();
     UserOperationLog::cleanHistoryLog();
-
+    bool sqlConnected= SQLHelper::Open();
+    if (sqlConnected)
+    {
+        AppGlobalValues::setDBconnected(true);
+    }
     w.showFullScreen();
     DeviceManager::Default()->initDevice();
 
diff --git a/src/windows/LoginDialog.cpp b/src/windows/LoginDialog.cpp
index 7723b33..d006299 100644
--- a/src/windows/LoginDialog.cpp
+++ b/src/windows/LoginDialog.cpp
@@ -162,16 +162,10 @@ void LoginDialog::clearInputData()
 void LoginDialog::doLogin()
 {
     if (!(AppGlobalValues::DBconnected().toBool())){
-        bool sqlConnected= SQLHelper::Open();
-        if (sqlConnected)
-        {
-            AppGlobalValues::setDBconnected(true);
-        }
-        else{
-            mErrorMessage->setText(QString(tr("Can't connect db. Please reboot the device and retry, or call for the service help.")).arg(LOGIN_LOCK_MINUTIES));
-            mErrorMessage->setVisible(true);
-            return;
-        }
+
+        mErrorMessage->setText(QString(tr("Can't connect db. Please reboot the device and retry, or call for the service help.")).arg(LOGIN_LOCK_MINUTIES));
+        mErrorMessage->setVisible(true);
+        return;
     }
     if(mLoginFailedCount >= LOGIN_LOCK_COUNT)
     {
diff --git a/src/windows/MainWindow.cpp b/src/windows/MainWindow.cpp
index 8109f86..affcdb7 100644
--- a/src/windows/MainWindow.cpp
+++ b/src/windows/MainWindow.cpp
@@ -35,7 +35,6 @@ MainWindow::MainWindow(QWidget* aParent)
     , mInitializWidget(new InitializeWidget(this))
     , mShutdownWidget(new ShutdownWidget(nullptr))
     , mAdminTabIndex(-1)
-    , mThread(nullptr)
     , mTabInited(false)
 {
     mUI->setupUi(this);
@@ -76,8 +75,6 @@ MainWindow::MainWindow(QWidget* aParent)
 
 MainWindow::~MainWindow()
 {
-    mThread->terminate();
-    mThread->deleteLater();
     delete mUI;
     delete mShutdownWidget;
 }
diff --git a/src/windows/MainWindow.h b/src/windows/MainWindow.h
index 4eb31d6..7addde5 100644
--- a/src/windows/MainWindow.h
+++ b/src/windows/MainWindow.h
@@ -62,7 +62,6 @@ private:
     ShutdownWidget* mShutdownWidget;
 
     int mAdminTabIndex;
-    QThread* mThread;
     bool mTabInited;