The SEA model of hypersonic aircraft X-43A is established based on statistical energy analysis (SEA) theory. Three parameters of the SEA model are established by the theory and experiential formula. According to the damping loss factors of model subsystem and the acoustic absorptivity of cavity, sensitivity analysis of vibro-acoustic response is discussed. The effect of vibro-acoustic response caused by the division way on plate subsystem and material structure are analyzed. The analysis results show that the material structure, damping loss factors and material type have a great effect on the characteristics of vibro-acoustic response. The division way of plate subsystem can affect computational accuracy greatly. The influencing factors should be synthetically considered in the design of acoustics structure.