The basic concept of the technique modeling the vibroacoustic system was described. According to the domain decomposition continuity conditions, this paper discussed pressure and velocity continuity and impedance continuity at the interface, and their corresponding coupled models were derived by using weighted residual formulation. And numerical analysis was carried out using finite element method by the software of LMS/SYSNOISE Rev 5.5. The results were in good agreement with FEM's results. Comparing both of the continuity conditions, the pressure and velocity coupling is more accurate for small models, while the latter one performs better for large models. Moreover, several simple optimal principles of domain decomposition were provided.