Abstract: The scanning mobility particle sizer was used to measure the size distribution of particles. It provided a method for analyzing filtration efficiency of sizing particles. The method was used to measure the penetration ratio and filtration efficiency of stainless steel filter material with the mixed particle size standards and the DOP polydisperse aerosols. The results show that the maximum penetration diameter (D_max) varies from different fiber size of metal filter material, the D_max becomes greater as fiber size is increased. When filtration velocity is in the range of 1-3 cm/s, the filtration efficiency and theD_max of metal filter material decrease as increasing of filtration velocity. The efficiency of each layer of multilayer filter material decreases stage by stage for polydisperse aerosol, but total efficiency increases with increase of layers. The results also show that the maximum penetration ratio of each layer increases with increase of layers.