Based on the principle of impedance mismatching, the performance of rigid vibration isolation mass in impeding vibration wave propagation was discussed from the perspective of wave approach. Based on FEM,the influence of its weight as well as the cross-section shape parameters on the isolation performance of rigid vibration isolation mass was studied through numerical simulation. The results show that rigid vibration isolation mass can effectively impede the propagation of the medium and high frequency vibration waves, and the heavier the vibration isolation mass, the better the isolation performance. For low frequency waves, the vibration isolation effect is not so obvious; for a rectangular vibration isolation mass, the isolation performance could be effectively improved by increasing the cross-section height and reducing the cross-section width. A useful reference was provided for the application of rigid vibration isolation masses to the vibration isolation and noise reduction of ship structure.