To study the mechanical properties of composite rock masses under dynamic impact, a three-dimensional SHPB simulation system was constructed using the FLAC-PFC coupling method. Based on the Weibull distribution and damage theory, an elastic damage constitutive model considering the non-uniformity of rocks was established. Dynamic impact simulations of composite coal-rock and composite rock-coal samples with different joint angles were conducted. The dynamic strength and crack propagation laws of samples with different joint angles after dynamic impact were compared and analyzed. The progressive damage evolution process of composite rock masses with different joint angles was obtained, and the energy dissipation characteristics of composite rock masses with different joint angles were given. The results show as follows. The three-dimensional SHPB model constructed by FLAC-PFC coupling is effective. The calculation results of the elastic damage constitutive model based on the Weibull distribution are compared with the experimental results to verify the correctness of the developed constitutive model. For composite rock masses with different joint angles, the damage zone begins to emerge on the coal side and expands along the joint until failure, achieving the characterization of the damage process of coal-rock under dynamic loading. For composite rock masses with different joint angles, the strain energy begins to concentrate on the coal side and expands along the joint until failure, demonstrating the spatial distribution of energy concentration and realizing the visualization of energy evolution.