Abstract：Based on wave analysis method, the characteristics of vibration wave propagation from typical hull structure are analyzed according to wave conversion and impedance characteristic in non-homogeneous structure, and the formula of sound transmission loss incident by plane bending wave is deduced. On this basis, the influence of impedance mismatch ship foundation on isolation performance is discussed. The results show that 十structure greatly impedes the bending wave propagation, and the redistribution of bending wave in mutated-section is mainly determined by natural impedance of the two plates. The resistance at the connection of ┻┳ structure increased and its isolation performance is better than十structure. The isolation performance of structure obviously increased with the increment of the impedance mismatch level of the mutated-section, therefore more sound transmission loss can be get by bringing in a number of mutation of cross-section. The impedance mismatch base aggravated wave conversion, scattering and reflection of vibration wave in the hull plates, so that the total isolation performance improved significantly. This article aims to provide reference for acoustic design of typical hull structure.