如果知道tostring 的字符串格式那么可以根据字符串格式转化成 DateTime
string timeText = DateTime.Now.ToString("yy/MM/dd HH:mm:ss");
DateTime DataTime = new DateTime(2011);
bool a= DateTime.TryParseExact(timeText, "yy/MM/dd HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out DataTime);