Abstract: The ideally undamaged stress-strain curve for concrete is obtained through experiments. Based on the undamaged curve and the damage mechanics theories, a new elastoplastic damage constitutive model for concrete is presented in which plasticity and damage are decoupled. The plasticity range is constructed in the effective stress space using the yield function with two hardening variables, and the hardening rule is given in the form of Ramberg-Osgood formulation on the basis of ideally undamaged state. The damage model is based on the decomposition of effective stress tensor. And two damage variables, one for tensile damage and the other for compressive damage are used to account for different damage states. The sectionalized damage evolution equations based on the undamaged state are driven by plastic strain. Finally the comparison between numerical simulations and experimental results illustrates the validity of the presented model.