Based on the theory of direct torque control (DTC) and vehicle system dynamics, a eletromechanical coupling simulation model of high-speed train was set up, which took the electric and mechanical properties of vehicle drive system into account. Some simulation studies and analyses for three different dynamic models of a high-speed EMUs were performed to study the effect of drive system for vehicle dynamics. The simulation results showed that the critical speed of the vehicle model which had drive system lower than the model which had no drive system, and the running safety and stability of the former were larger than the latter. When vehicles under the condition of high speed operation, compared with the vehicle model which had no drive system, the horizontal and vibration acceleration amplitudes of the model which had drive system were larger, especially the most obvious change was frame. As a result of the existence of the drive system, it made the frame and drive system coupling in many frequency ranges, causing the vibration of the frame to strengthen. It also showed that driving force basically had no effect on vehicle dynamic characteristics.