Abstract: The display color gamut determines the range of colors that the monitor displays. Since the color CRT and LCD work differently, the same RGB values show different colors on different displays. Extensive measurements for different color specimens of different displays were carried out by experimental methods, and the characteristics and color gamut of LCD and CRT were compared. The results show that the color gamut of LCD display is smaller than that of CRT, the image colors shown on CRT can not be shown on the LCD, and the color brightness, saturation and tonal range are also different.