diff --git a/sane/scanner.cpp b/sane/scanner.cpp
index bfa10a5..2cfeaeb 100644
--- a/sane/scanner.cpp
+++ b/sane/scanner.cpp
@@ -21,6 +21,8 @@
 #pragma comment(lib, "Shlwapi.lib")
 
 
+#define START_SCAN_IN_THREAD
+
 static IMPLEMENT_OPTION_STRING_COMPARE(compare_sane_opt);
 
 #define SET_SANE_OPT_ID(id, id_name, name, val, extension)		\
@@ -490,6 +492,10 @@ scanner::scanner(SCANNERID id) : handle_(NULL), id_(id), ex_id_(EXTENSION_ID_BAS
 scanner::~scanner()
 {
 	close();
+	if (thread_starting_.get() && thread_starting_->joinable())
+		thread_starting_->join();
+	thread_starting_.reset();
+
 	if (cfg_)
 	{
 		cfg_->release();
@@ -1388,6 +1394,67 @@ int scanner::set_is_multiout(bool enable)
 	return ret;
 }
 
+int scanner::thread_start(void)
+{
+	int ret = hg_sane_middleware::instance()->start(handle_, NULL);
+
+	// the third-APPs in linux will call 'stop' after every start, but it not happens in windows-apps, so we handle this as following ...
+	if (ret == SANE_STATUS_NO_DOCS && prev_start_result_ == SANE_STATUS_GOOD)
+		ret = hg_sane_middleware::instance()->start(handle_, NULL);
+
+	if (ret == SANE_STATUS_GOOD)
+	{
+		/*if (indicator_.get() && !IsWindowVisible(indicator_->hwnd()))
+			indicator_->show(true);*/
+
+		unsigned int l = sizeof(img_fmt_);
+		SANE_CompressionType cmprsn = img_fmt_.compress.compression;
+		if (hg_sane_middleware::instance()->io_control(handle_, IO_CTRL_CODE_GET_FINAL_IMAGE_FORMAT, &img_fmt_, &l))
+			img_fmt_.img_format = SANE_IMAGE_TYPE_BMP;
+		img_fmt_.compress.compression = cmprsn;
+	}
+	//else if (indicator_.get())
+	//{
+	//	indicator_->notify_scan_over(hg_scanner_err_description(ret), true);
+	//}
+	else
+	{
+		// display error message on progress UI, may be closed immediately by APP, so we hide progress UI and call message_box ...
+		// 
+		//if (callback::show_progress_ui && is_bIndicator)
+		//{
+		//	int ev = SANE_EVENT_WORKING;
+		//
+		////	on_ui_event(ev, (void*)ev);
+		//	ui_notify(SANE_EVENT_SCAN_FINISHED, (void *)hg_scanner_err_description(ret), ret);
+		//}
+		//else
+		{
+			if (callback::close_ui)
+				callback::close_ui(UI_INDICATOR);
+
+			if (callback::show_messagebox_ui)
+			{
+				callback::show_messagebox_ui(app_wnd_, ret, (void*)hg_scanner_err_description(ret), 0);
+			}
+			else
+			{
+				std::wstring	msg(local_trans::a2u(hg_scanner_err_description(ret), CP_UTF8));
+
+				//if (indicator_.get())
+				//	indicator_->show(false);
+				if (!IsWindow(app_wnd_))
+					callback::bring_message_box_topmost(local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str());
+				MessageBoxW(app_wnd_, msg.c_str(), local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str(), MB_OK | MB_ICONERROR);
+			}
+		}
+		is_scanning_ = false;
+	}
+	prev_start_result_ = ret;
+
+	return ret;
+}
+
 scanner::EXAPIPOS scanner::find_ex_api(int op_id)
 {
 	return std::find(ex_opts_.begin(), ex_opts_.end(), op_id);
@@ -2452,64 +2519,18 @@ COM_API_IMPLEMENT(scanner, int, start(void))
 	scan_err_ = false;
 	user_cancel_ = false;
 	fetch_imgs_ = 0;
+	is_scanning_ = true;
 	app_wnd_ = setting_.get() ? setting_->hwnd() : callback::find_main_wnd();
-	ret = hg_sane_middleware::instance()->start(handle_, NULL);
 
-	// the third-APPs in linux will call 'stop' after every start, but it not happens in windows-apps, so we handle this as following ...
-	if(ret == SANE_STATUS_NO_DOCS && prev_start_result_ == SANE_STATUS_GOOD)
-		ret = hg_sane_middleware::instance()->start(handle_, NULL);
+	if (thread_starting_.get() && thread_starting_->joinable())
+		thread_starting_->join();
+#ifdef START_SCAN_IN_THREAD
+	thread_starting_.reset(new std::thread(&scanner::thread_start, this));
+#else
+	ret = thread_start();
+#endif
 
-	if (ret == SANE_STATUS_GOOD)
-	{
-		/*if (indicator_.get() && !IsWindowVisible(indicator_->hwnd()))
-			indicator_->show(true);*/
-
-		unsigned int l = sizeof(img_fmt_);
-		SANE_CompressionType cmprsn = img_fmt_.compress.compression;
-		if (hg_sane_middleware::instance()->io_control(handle_, IO_CTRL_CODE_GET_FINAL_IMAGE_FORMAT, &img_fmt_, &l))
-			img_fmt_.img_format = SANE_IMAGE_TYPE_BMP;
-		img_fmt_.compress.compression = cmprsn;
-	}
-	//else if (indicator_.get())
-	//{
-	//	indicator_->notify_scan_over(hg_scanner_err_description(ret), true);
-	//}
-	else
-	{
-		// display error message on progress UI, may be closed immediately by APP, so we hide progress UI and call message_box ...
-		// 
-		//if (callback::show_progress_ui && is_bIndicator)
-		//{
-		//	int ev = SANE_EVENT_WORKING;
-		//
-		////	on_ui_event(ev, (void*)ev);
-		//	ui_notify(SANE_EVENT_SCAN_FINISHED, (void *)hg_scanner_err_description(ret), ret);
-		//}
-		//else
-		{
-			if (callback::close_ui)
-				callback::close_ui(UI_INDICATOR);
-
-			if (callback::show_messagebox_ui)
-			{
-				callback::show_messagebox_ui(app_wnd_, ret, (void*)hg_scanner_err_description(ret), 0);
-			}
-			else
-			{
-				std::wstring	msg(local_trans::a2u(hg_scanner_err_description(ret), CP_UTF8));
-
-				//if (indicator_.get())
-				//	indicator_->show(false);
-				if (!IsWindow(app_wnd_))
-					callback::bring_message_box_topmost(local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str());
-				MessageBoxW(app_wnd_, msg.c_str(), local_trans::lang_trans_between_hz936(CONST_STRING_START_FAILED).c_str(), MB_OK | MB_ICONERROR);
-			}
-		}
-	}
-	prev_start_result_ = ret;
-	is_scanning_ = ret == SANE_STATUS_GOOD;
-
-	return local_utility::sane_statu_2_scanner_err(ret);
+	return ret;
 }
 COM_API_IMPLEMENT(scanner, int, stop(void))
 {
diff --git a/sane/scanner.h b/sane/scanner.h
index 79a3699..4eb4f1f 100644
--- a/sane/scanner.h
+++ b/sane/scanner.h
@@ -104,6 +104,9 @@ class scanner : public ISaneInvoker, virtual public refer
 	int set_option_value(int sn, SANE_Value_Type type, int size, void* data);
 	int set_is_multiout(bool enable);
 
+	int thread_start(void);
+	std::unique_ptr<std::thread>	thread_starting_;
+
 	typedef struct _ex_api
 	{
 		unsigned int	ind;