Abstract: Concrete is a typical porous medium permeated by an interconnected network of pores which have great influences on elastic modulus, strength and other mechanical parameters of concrete across both micro and macro scale. Concrete was considered as a three-phase composite with aggregates, pores and mortar matrix. Pores, micro crack, micro flaw and aggregates were put into the mortar matrix randomly by the Monte Carlo simulation method, and the effective mechanical properties of porous material was derived according to the three-phase sphere model and hollow cylindrical rod model. Then the effective constitutive model of porous material was established, and finally the meso element equivalent model of porous concrete specimen was built. Thus two-grade porous concrete specimen in uniaxial tensile and compression was analyzed by means of nonlinear method. The results indicated that the existence of pores and micro cracks had great influence on macro elastic modulus, strength and residual strength of concrete, which should not be neglected when analyzing the macro-mechanical properties and damage fracture of concrete.