Abstract: A Statistical Energy Analysis (SEA) model was established for a real vehicle. The main propagation paths were classified by the analysis of propagation characteristics, and the simplified model approximation analysis was performed. By choosing the main and secondary systems in the SEA model, two simplified models are established, and the calculation of their interior noise and propagation path shows that the characteristics of the model subsystem change, the energy propagation path and size characteristics change, and even the subsystem's ability to accept the external fluid pulsation and sound field changes, resulting in the change of the calculated interior noise. The use of the simplified model requires further study.