Abstract: To investigate the strength and failure characteristics of double cracked rock mass under different defect angles, C++ language is employed to develop an elastic-brittle damage constitutive model inner FLAC^3D. The concept of basic unit and rupture unit are pulling into this model. The mechanical behavior of meso rock units before fracture is assumed to be elasticity, and the rupture property is assumed to be elastic brittleness. The basic units are converted into rupture units while the stress state reaches the strength criterion and its mechanical parameters are correspondingly weakened. The mechanics parameters of rupture units maintain at the level of residual strength. The numerical simulation results indicate that the rock mass strength decreases first and then increases with the increase of the defect angle, while the meso-fracture transforms from the tensile-shear mixed failure to the shear failure.