Abstract: On the basis of Mohr model, a simulation of discontinuous deformation is studied using the FLAC^3D inner interface model and the secondary development platform of the FISH language-compiles program included in FLAC^3D software. The problem of dynamic modeling of interface elements in FLAC^3D is solved, and uniaxial compression tests and comparative studies are carried out. The analytical results reveal that the discontinuous deformation simulation method based on FLAC^3D is effective and feasible. The simulated results are similar to the experimental ones, and the proposed method can effectively catch the developing process of cracking. This study provides an new view for simulation of discontinuous deformation.