// minimized 表示窗口最小化

   this.WindowState = FormWindowState.Minimized;

      //定义一个布尔变量用来切换最大化和默认值

      bool b = true;

         private void button2_Click(object sender, EventArgs e)

         {

             if (b)

             {

                //最大化

                 this.WindowState = FormWindowState.Maximized;

                 b = false;

             }

             else

             {

                //默认值

                 this.WindowState = FormWindowState.Normal;

                 b = true;

             }

         }