The relationship between Bidirectional Reflectance Distribution Function (BRDF) and Laser Rader Cross Section (LRCS) is introduced by means of the electromagnetic radiation and scattering theories. The experimental measurements are made for BRDF of various samples with roughness at wavelength of 0.63 μm, and the influences of the surface height standard deviation, the correlation length and dielectric constant on BRDF are considered. The partial measured data are in good agreement with theorical calculation.