The strength and stress-strain relationship of saturate concrete is investigated in this paper. The influence of moisture to concrete strength is assumed to be related to cement surface energy reduction by water. The initial elastic modulus of concrete is obtained by considering the deformation of both pore and microcracks in concrete. The stress-strain relationship is achieved with damage mechanics by comparing the damage evolution rules between dry and saturated concrete under external loading. The comparison between experiments and the results by the model proposed in this paper indicates a favorable agreement.