Abstract: Any attempt to find out the potential problem or weakness of the systems and the shipboard equipments to ensure the battle effectiveness of naval ship, a numerical simulation of antiishock performance prior to a shock test however is necessary to avoid damages to the marine systems without knowing their actual anti-shock performance. This paper presents a numerical simulation in time domain to investigate the anti-shock performance of marine gear case. A geometric model of the gear case was built using MDT software and was preprocessed and finite element mesh generated by hyper mesh software. The anti-shock performance of the gear case was computed numerically in time domain by ABAQUS software. Shock response of the typical regions was obtained based on the calculation results. The weak links were found out through the simulation results. This research may provide a reference for further optimization design of marine gear case.