The mechanical behaviors of mortar subjected to coupled sulfate attack and dry wet cycles are investigated. The various parameters include the number of dry wet cycles and the concentration of sulfate solution. Based on the continuum damage mechanics theory and experimental data, the elastoplastic chemical damage constitutive model is proposed for cementitious materials under sulfate corrosion. Comparison between numerical simulations and tested results reveals that the proposed model can well predict the elastic, plastic and damage characteristics of corroded cementitious materials under compressive force.