The method of evaluating the night vision imaging system (NVIS) compatibility of LCD is analysed in theory, and a method of comparing the contributiveness for NVIS radiance of every monochromatic chip in orange, green and blue (OGB) polychrome LED is pointed out. A LCD with two backlight sources system including white LEDs and OGB polychrome LEDs is prepared to for experiment. It is proved that, when white LEDs are used as backlight source, the NVIS radiance of LCD is 3.14× 10-8 W/(cm2 ·sr·nm), which is larger than the limit of 2.2× 10-9 W/(cm2 ·sr·nm) in national military standard (GJB), when OGB polychrome LEDs are used as backlight source, the NVIS radiance reduces to 1.958 × 10-9 W/(cm2 · sr · nm), which is accordant with the requirement in GJB. The contribution for NVIS radiance of every monochromatic chip in OGB polychrome LED is compared, the results show that blue chip contributes the most NVIS radiance, red chip less, and green chip the least.