Honeycomb structure on the inner wall of baffle dominates the performance of stray light suppression of the baffle. It is significant to understand the anisotropic radiation transfer characteristics of the honeycomb cell for stray light analysis and optimum design of baffle. A numerical model of radiative propagation was built for honeycomb cell and the discrete BRDF expression was deduced for the equivalent surface. By simulating the stray light propagation with the Monte Carlo method, the effects of geometric parameters and reflectivity of coating on BRDF of the equivalent surface were analyzed. Based on the obvious backscattering of the honeycomb structure predicted by the BRDF analysis, the probability model of anisotropic reflection was established for the equivalent surface. The BRDF results predicted by the probability model show good agreement with that of the direct simulation, and it can be well used in stray light analysis and design of baffle.