1.[DllImport("user32.dll")]//取设备场景
2.PRivate static extern IntPtr GetDC(IntPtr hwnd);//返回设备场景句柄
3.[DllImport("gdi32.dll")]//取指定点颜色
4.private static extern int GetPixel(IntPtr hdc, Point p);

Timer tim = new Timer();
tim.Interval = 1;
tim.Tick += delegate
{
Point p = new Point(MousePosITion.X, MousePosition.Y);//取置顶点坐标
IntPtr hdc = GetDC(new IntPtr(0));//取到设备场景(0就是全屏的设备场景)
int c = GetPixel(hdc, p);//取指定点颜色
int r = (c & 0xFF);//转换R
int g = (c & 0xFF00) / 256;//转换G
int b = (c & 0xFF0000) / 65536;//转换B
pictureBox1.BackColor = Color.Fromargb(r, g, b);
};
tim.Start();