diff --git a/func/Module_mainwindow.py b/func/Module_mainwindow.py
index 056972e..214dad5 100644
--- a/func/Module_mainwindow.py
+++ b/func/Module_mainwindow.py
@@ -280,7 +280,9 @@ class MainWindow(QMainWindow, Ui_Signal_Label):
             return
 
         sub_folders = [item.name for item in Path(path).iterdir() if item.is_dir()]
+        self.ui.comboBox_sampID.clear()
         self.ui.comboBox_sampID.addItems(sub_folders)
+        self.ui.comboBox_sampID.setCurrentIndex(0)
 
     def check_root_path(self):
         if self.ui.plainTextEdit_root_path.toPlainText() == Constants.STRING_IS_EMPTY: