Abstract: In order to consider local plastic deformation of rocks on mesoscopic level,a constitutive model of elasto-plastic damage based on the incremental theory was deduced in strain space,and the failure elements deleting method was used to simulate crack propagation in program so as to explicitly show the extension of the cracks in rocks.By following a simple elasto-brittle constitutive relation,the complete progressive failure of 3D rock was obtained.Finally,three-point bending beam experiments were conducted.Complete nonlinear stress-strain curves as well as facture images during the damage evolution process were obtained.It was by the numerical simulation results shown that 3D failure process was much more complicated than 2D failure process.The proposed model was a useful and effective tool to simulate the failure process of heterogeneous materials.