To simulate the dynamic responses of the EMU structure by using the commercial finite element method is a hard work because of huge computation cost and low efficiency, especially when the mesh of vehicle body is refined or the solid element is adopted. To solve this problem, the dynamic multi sub-model method is proposed in this work to analyze the dynamic responses of the local structure of EMU. By using the proposed method, the fluid loads in typical conditions is transferred from global structure to local structure step by step and the dynamic responses of local structure are simulated. Numerical simulation results indicate that by using the solid element and adopting the boundary conditions from global analysis compared with the shell element, many detail features of the local structure, such as fillets, welds, bolts and etc., can be revealed properly. Therefore, the stress distribution of local structure under dynamic load can be revealed. The results accuracy based on Saint-Venant principle from different elements and different levels is validated. This work is a foundation to perform the optimization of the vehicle body or to evaluate the fatigue life of local structure at high speed.