For the scattering process of light through the two rough surfaces consisted of semitransparent coatings and rough substrate, considering the shading effect and multiple scattering, Monte Carlo model of surface scattering was established based on surface generation method.The reflected light distribution of the semitransparent coatings on rough substrate was obtained.The effects of coatings thickness, surface roughness and incident light wavelength on Bidirectional Reflectance Distribution Function (BRDF) were studied.Simulation results show that BRDF is largely affected by surface roughness, and the reflection peak decreases linearly with the root-mean-square slope of the surface.The semitransparent coatings thickness changes the value of BRDF.When the thickness is equal to one-tenth of the wavelength, BRDF reaches the minimum value.The local distribution of BRDF in the specular reflection direction with near-infrared light illumination tends to broaden up in comparison with visible light illumination, and the directional hemispherical reflectance with near-infrared light illumination is also larger.