Abstract: In multi-phase porous saturated concrete, pore water in the saturated concrete has a remarkable influence on the mechanical property of concrete. Based on the basic principles of damage mechanics, an elasto-plastic damage constitutive model for water-saturated concrete under uniaxial compression is established. Combined with the Terzaghi’s effective stress principle, it is found that the effective stresses of the body and structure lead to the damage of material. According to the stress equilibrium condition, the two kinds of effective stress relationship are attained. And on this basis, the damage evolution equation of water-saturated concrete under uniaxial compression is established.