The hybrid finite-discrete element method Y-2D/3D IDE is applied to model the dynamic fracture of rock specimens with various geometries during impacting a fixed rigid surface. It is found that the modelled primary fractures are highly dependent on the rock geometry determining the weakest plane for a given impact, which agrees well with others' experimental and SPH numerical results. Compared with others' SPH results, Y-2D/3D IDE better simulates the actinomorphic pattern of primary fractures around the impact area and the secondary & tertiary fractures observed in the dynamic fracture experiments. It is concluded that the proposed Y-2D/3D IDE is a valuable tool to model rock dynamic fracture compared with FEM and DEM.