According to the suffered various impacts and vibrations of traction driving part in high-speed train under complex operating environments and conditions, the modal problems in the rotor of traction motor, power output device in traction transmission system, working in high-speed trains is investigated. In this paper, a Finite Element Analysis model for rotor modal simulation research is established, by using which the influences of structure parts on motor natural frequency is analyzed. From the simulation analysis, the natural frequencies, the vibration mode and the amplitude of each order modes are obtained, which could provide a theoretical basis for the rapid, stable and safety operation of high-speed trains.