Abstract: The relationship between hydraulic conductivity of a porousmaterial and its number-size is simulated by using the finite element method.The solid matrix and the pore space are generated randomly according tothe materialporosity, and the material parameters and the element properties areassigned by theANSYS parameter design language. The equivalent hydraulic conductivity iscomputed according to the flow flux through some section computed by FEM andDarcy law, and the relationship between the equivalent hydraulicconductivity and the porosity number-size of porous materials is obtained.The numerical simulation shows that the equivalent hydraulicconductivity is directly proportional to the square of the porosity size whilethe porosity is constant, for which the proposed conclusion agrees well withempirical expressions. The equivalent hydraulic conductivity is directlyproportional to the porosity while the porosity size is constant.