Mechanical noise caused by power equipment vibration is the main source of underwater radiated noise of the ship, and vibration isolation and noise reduction of ship equipment has been widely concerned. Therefore,a vibration isolation system designed for four sets of auxiliary engine of ship cabin was investigated in the paper, aimed to further reveal the influence of various parameters including floating raft shell thickness, excitation source, and different ship hull and installation platform thickness on the vibration level difference of system. The results obtained from numerical analysis using MSC software and experiment indicate that one-dimensional spring element simplified can properly simulate the actual rubber vibration isolator on low frequency bands, and increasing thickness of flat, hull and platform can improve the effect of vibration isolation obviously.