The lattice Boltzmann method was used to simulate low Reynolds number gas flows through ceramic filter matrixes.The porous structure was generated randomly by computer under the simplification that the ceramic filter matrix was composed of numerous spheres with equal diameter.The relation between Reynolds number and friction factor was calculated，and the calculated values agreed well with analytical values of Blake-Kozeny equation and Ergun equation.The change of microscopic velocity in pores was obtained.In pores，the velocity distributions were parabolic curves approximately and they would reach the maximum on the section of the minimum effective diameter.At one specific point in pores，the ratio of its local velocity to superficial velocity was fixed.