DateTime dt = DateTime.Now; //本月第一天时间 DateTime dt_First = dt.AddDays(-(dt.Day) + 1); Label1.Text = dt_First.ToString("yyyy-MM-dd"); //将本月月数+1 DateTime dt2 = dt.AddMonths(1); //本月最后一天时间 DateTime dt_Last = dt2.AddDays(-(dt.Day)); Label2.Text = dt_Last.ToString("yyyy-MM-dd"); int weeknow = Convert.ToInt32(System.DateTime.Now.DayOfWeek); int daydiff = (-1) * weeknow + 1; int dayadd = 7 - weeknow;  //本周第一天 lblBegin.Text = System.DateTime.Now.AddDays(daydiff).ToString("yyyy-MM-dd"); //本周最后一天 lblEnd.Text = System.DateTime.Now.AddDays(dayadd).ToString("yyyy-MM-dd");