In this paper, diffuser with taper microstructure has been put forward, and the transmission of the light in the taper microstructure has been analyzed. The software of Lighttools has been used to analyze the influence on light intensity distribution of the vertex angle θ, the space between the microstructure L, the diameter ratio of up to down of the microstructure A/B, the cutting output of the microstructure H and the refractive index of the diffuser n1.As a result, the light intensity of the optical axis will increase and visual angle will decrease when the vertex angle θ, the refractive index of the diffuser n1 and the cutting output of the microstructure H increase; the light intensity of the optical axis will increase and visual angle will decrease when the space between the microstructure decrease; with the increasing of the ratio A/B, the light intensity of the optical axis would first increase and then decrease, visual angle would first decrease and then increase. When A/B=0.4, the light intensity gets the maximum value, the visual angle gets the minimum value. The result of the simulation is significant to manufacture and research.