Abstract: To investigate the effect of arc cracks on mechanical properties and crack propagation of fractured rock mass, the strain softening model and the null model in FLAC^3D software are adopted respectively to describe the mechanical behavior of the rock and crack, and the plastic zone is regarded as the basis for crack propagation. This numerical calculation model is adopted to study the effect of arch height, chord length and inclination on the crack propagation path and rock mass mechanical behavior under uniaxial compression. The calculation results are as follows: the peak strength of the sample decreases as the arch height increases, and the chord length also affects the peak strength. The crack inclination has an effect on the expansion path of arc cracks. The peak strength of the sample increases when the inclination becomes larger. Finally, the model test is used to verify the rationality of the simulation results.