DateTime start=DateTime.Now;
//这里写程序执行代码
DateTime end=DateTime.Now;
TimeSpan last=end-start；
string result="执行了"+last.Minute+"分"+last.Second+"秒";

------解决方案--------------------
搜一下Stopwatch这个类，就是秒表了。

------解决方案--------------------
C# code

    //the start time
    DateTime startTime = DateTime.Now;
    Console.WriteLine(startTime);

    //the end time. 
    DateTime stopTime = DateTime.Now;
    Console.WriteLine(stopTime);

    System.TimeSpan duration = stopTime - startTime;
    // 总共多少分钟
    Console.WriteLine("minutes:" + duration.TotalMinutes);
    //总共多少秒钟
    Console.WriteLine("seconds:" + duration.TotalSeconds);

------解决方案--------------------
可以用Stopwatch活着TickCount,这里有个例子
http://blog.csdn.net/jinjazz/archive/2007/12/10/1927126.aspx

------解决方案--------------------
2楼和4楼的朋友回答的很好,我这里有一个实际的例子:

C# code

        private void button1_Click(object sender, EventArgs e) //查询语句;
        {
            this.Cursor = Cursors.WaitCursor; //获取鼠标的形状,为沙漏形状
            DateTime KaiShi = DateTime.Now;
            ChaXun_HZ();
            DateTime Eend = DateTime.Now;
            TimeSpan XiangCha = Eend - KaiShi;
            string zhixing = XiangCha.Minutes + "分" + XiangCha.Seconds + "秒";
            this.Cursor = Cursors.Default; //获取鼠标为正常形状
            MessageBox.Show("此查询一共用时:"+zhixing,"提示");
        }

------解决方案--------------------
System.Diagnostics.Stopwatch