Triaxial compression tests of mortar specimens under various hydrochemical environments were carried out. The effects of the pH、concentration and composition of chemical solution on the corrosiveness and micro/meso structure of the mortar specimens were evaluated. The hydrochemical corrosion mechanisms of the mortar specimens were explored and the results revealed further influence of various hydrochemical actions on physical and mechanical parameters of the mortar specimens. A new damage parameter was proposed based on the mortar secondary porosity caused by chemical corrosion, which can quantify the evolution process of the physical & mechanical parameters of the mortar specimens during its hydrochemical damage.