Abstract: In this paper homogenous and dense diamond films with good crystalline quality were successfully deposited on porous silicon(PS) surfaces by the microwave plasma assisted chemical vapor deposition(MPCVD) method.Photoluminescence measurements show that the CVD diamond film-coated porous silicon has a weak shift of emission peak wavelength as compared with the stored porous silicon without a diamond film, and its PL peak intensity almost does not change with time. It means the diamond film can efficiently stabilize the porous silicon and provide a passivation effect. In addition,due to its well-known high hardness,the CVD diamond film can improve the mechanical strength of PS surface, therefore it is a promising candidate for passivation of porous silicon in the future.