OpenFileDialog FileDialog = new OpenFileDialog();
string Path_Log = Path_Desktop + "/tvpost/log";
FileDialog.InitialDirectory = Path_Log;
FileDialog.Filter = "|*.xlsx";
FileDialog.Multiselect = false;
FileDialog.Title = "请选择需要导入的.xlsx文件";
if (FileDialog.ShowDialog() == DialogResult.OK)
{
//如果选择文件，执行操作。
}