The backlight module of high dynamic range video display system based on the geometrical optics is designed and accomplished. First, the important influence of luminance uniformity of backlight module on the high dynamic range video display system is determined. And the design parameters, such as the spacing and the light mixing distance of LED light sources of backlight module, are determined by Sparrow′s criterion. Then, the AutoCAD software is used to conduct 3D modeling. TracePro and LightTools are taken in the simulation experiment. The high dynamic range video display system is built by modifying the backlight module of the existing display screen. The results show that the designed and accomplished backlight module in this paper can meet the requirements of high dynamic range video display system. Peak brightness of liquid crystal display panel can reach 2500 cd·m-2 and uniformity of luminance is up to 95.85%.