diff --git a/hgsane/sane_hg_mdw.cpp b/hgsane/sane_hg_mdw.cpp
index 8d52db6..33ebeba 100644
--- a/hgsane/sane_hg_mdw.cpp
+++ b/hgsane/sane_hg_mdw.cpp
@@ -140,6 +140,11 @@ namespace local_utility
 
 		return malloc(bytes);
 	}
+	void free_memory(void* m)
+	{
+		if (m)
+			free(m);
+	}
 
 
 	/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -1020,7 +1025,7 @@ hg_sane_middleware::~hg_sane_middleware()
 
 	for (size_t i = 0; i < opts_.size(); ++i)
 	{
-		free(opts_[i].desc);
+		local_utility::free_memory(opts_[i].desc);
 	}
 	for (size_t i = 0; i < openning_.size(); ++i)
 		hg_scanner_close(openning_[i].handle, true);
@@ -1379,6 +1384,26 @@ SANE_Option_Descriptor* hg_sane_middleware::number_option_to_SANE_descriptor(con
 	return sod;
 }
 
+void hg_sane_middleware::on_device_closed(scanner_handle h)
+{
+	// 由于目前对多设备的支持还不是刚需，故代码只考虑单设备情况，设备关闭后，清除所有变量
+	for (size_t i = 0; i < opts_.size(); ++i)
+	{
+		local_utility::free_memory(opts_[i].desc);
+	}
+	opts_.clear();
+	for (size_t i = 0; i < openning_.size(); ++i)
+	{
+		if (openning_[i].handle == h)
+		{
+			openning_.erase(openning_.begin() + i);
+			i--;
+		}
+	}
+	cur_vals_.clear();
+	slave_options_.clear();
+	master_options_.clear();
+}
 SANE_Status hg_sane_middleware::open(SANE_String_Const devicename, SANE_Handle* handle, const char* name, const char* pwd, const char* method, char* rsc)
 {
 	scanner_handle	h = NULL;
@@ -1814,6 +1839,8 @@ SANE_Status hg_sane_middleware::close_device(SANE_Handle h)
 
 	if (hs)
 		err = local_utility::scanner_err_2_sane_statu(hg_scanner_close(hs, true));
+	if (err == SANE_STATUS_GOOD)
+		on_device_closed(hs);
 
 	return err;
 }
diff --git a/hgsane/sane_hg_mdw.h b/hgsane/sane_hg_mdw.h
index 35eeedf..d707cce 100644
--- a/hgsane/sane_hg_mdw.h
+++ b/hgsane/sane_hg_mdw.h
@@ -69,6 +69,7 @@ class hg_sane_middleware
 	static double sane_fixed_2_double(SANE_Fixed v);
 	static std::string option_value_2_string(SANE_Value_Type type, void* val);
 
+	void on_device_closed(scanner_handle h);
 	SANE_Status open(SANE_String_Const devicename, SANE_Handle* handle, const char* name, const char* pwd, const char* method, char* rsc);
 	SANE_Option_Descriptor* from_json(scanner_handle h, json* jsn, int opt_no);
 	scanner_handle find_openning_device(SANE_Handle h, bool rmv = false, OPENDEV* dev = NULL);