Abstract: On the principle of impedance mismatching, the performance that rigid vibration isolation mass impedes vibration wave propagation was researched. Rigid vibration absorber which means adding rigid vibration isolation mass at the region ship pedestal connected with the ship structure was brought in ship elastic pedestal. Based on FEM, the vibration propagation characteristics of the pressure hull as well as pedestal plates were stud ied through numerical simulation. The results show that, for medium-high frequency structure noise, such mass can effectively reduce the vibration and sound radiation of the pressure hull, while in low frequency, vibra tion isolation effect of the mass is not so obvious. The results can be used for reference to rigid vibration isolation mass applying to the vibration and noise reduction of ship structure