Abstract: In order to solve the problem that the traditional fracture criterion is difficult to simulate the mixed multi-crack propagation, based on the existing numerical manifold method program, the existing crack propagation criterion is improved so that the numerical manifold method can be adapted to the simulation of various types of crack propagation. Based on the Mohr-Coulomb criterion and the maximum circumferential stress criterion, the crack propagation direction is determined by combining the two criteria. The corresponding program developed by C language is used to calculate the half disk tensile tests and four-point bilateral shear tests. The crack propagation paths of the numerical simulation and test results are consistent, and the crack can pass through the interior of manifold element. Subsequently, the cracking problem of gravity dams is simulated, and it is found that the cracking of gravity dams is mainly tensile failure, and the crack propagation path is similar to the finite element results. Finally, by simulating the slope slip problem, the calculated results are highly consistent with those by DEM and other methods. The results of this study verify the effectiveness of the proposed strength criterion in simulating various types of crack propagation problems and lay a foundation for NMM to simulate practical engineering problems.