To study the mechanical properties of composite rock mass under dynamic loading, a three-dimensional SHPB simulation system is constructed using FLAC-PFC coupling. Considering the inhomogeneity of rock materials, an elastic damage constitutive model is established, and the dynamic loading tests for composite rock mass with different joint angles are carried out. The dynamic strength and crack propagation of composite rock mass with different angles are analyzed under dynamic loading. The progressive damage evolution process of composite rock mass with different joint angles is obtained, and the energy dissipation characteristics of composite rock masses with different joint angles are given. The results show that the validity of the three-dimensional SHPB model is verified, and the correctness of the developed constitutive model is verified by comparing the calculation results of the elastic damage constitutive model based on Weibull distribution with the experimental results. For the composite rock mass with different joint angles, the damage area begins to sprout on the side of the coal body and expands along the joint until failure, which realizes the three-dimensional characterization of the damage process of composite rock mass under dynamic loading. For the composite rock mass with different joint angles, strain energy begins to concentrate on the coal side and expands along the joint until failure, showing the three-dimensional spatial distribution of energy concentration and realizing the three-dimensional visualization of energy evolution.