By designing the stiffness of elastic suspension for the transformer under an intercity train, the natural frequency range of the transformer system (suspension frequency) based on the vibration isolation theory was determined during the design process. Then, the design scope of suspension stiffness was obtained according to the suspension frequency range and different suspension stiffness was established. The frequency response characteristics of bodywork floor under transformer excitation and the running comfort of the vehicle under air spring excitation were analyzed and compared. According to the results of comparative analysis, the optimal suspension frequency of the suspension system was 5 Hz. By comparing the vehicle using this elastic suspension with the vehicle using rigid suspension, the vertical vibration acceleration of the bodywork floor was greatly attenuated and the running comfort of the vehicle was obviously improved, which indicated that the design method adopted was correct.