To improve the interfacial adhesive strength between cellular matrix and filler in rigid polyurethane foam, the surface of filler was treated with coupling agent. Silane and titanate derivatives were used as coupling agents. The influence of addition of surfactant to coupling agent on the adhesive strength was also examined. The effect of surface treatment on the compressive properties of polyurethane foams were discussed by examining the combining equation of Padawer & Beecher''s and Rusch''s equations; the former equation could be applied to the matrix filled with discontinuous platelet filler, the latter generally to the foams. In case of reinforced foam, by treating the surface of platelet filler with coupling agents, both compressive modulus and compressive strength were found to be improved. Compressive property of foam the filled with titanate treated mica was better than that of foam filled with silane treated mica. It was found that the surfactant has an excellent effect on the compressive properties. The cell structure was obviously destroyed when more than 20wt. % of mica was loaded.