Based on the optical analysis software of LightTools, the transmitting processing of light in CD-pattern microstructure diffuser is analyzed. The injection molding process is used to verify the effect of this model. The effect of CD pattern microstructure on the light extraction efficiency is studied. Through theoretical research, simulation, and experimental comparison, the surface microstructure of the diffuser is modeled and the ray tracing is carried out on a large scale. The results show that, in the 80 mm×80 mm illumination area, the optical lumen efficiency of the CD pattern microstructure diffuser is obviously improved compared with that of the non-microstructure diffuser, and the line width of 200 μm can increase the optical lumen efficiency by 13.52%. According to the optimal simulation size, a CD pattern microstructure diffuser composed of several concentric rings is prepared, and an 8-inch LED downlight is used as the test luminaire. The total lumen output of the micro-structure diffuser, general diffuser, and luminaire without the diffuser is measured by the integrating sphere. The results show that the CD-pattern micro- diffuser has a transmittance of 90.6%, and its light transmittance is 8.8% higher than that of the general diffuser.