Abstract: Based on the principle of statistical energy analysis for conservatively or non-conservatively coupled systems,SEA models containing two subsystems and that including five ones are established for a panel-sideframe coupling structure.The research is focused on the energy relationship between the two models to make it possible that conservative or non-conservative coupling loss factors associated with a complicated coupling system can be obtained from a simple system, but similar to the complex one. Results from both the theoretical analysis and experiments show that the conservative coupling loss factor from the panel to the sideframe is 4 times that from the former to the latter one,and a similar quantitative relationship between non conservative coupling loss factors can also be obtained after into account taking the effective proportional factor,which is induced by the coupling damping.As a rational support of the study,good agreement between the two results is found.