Abstract: To study the influence of the parameters of suspended equipment under carbody on the elastic vibration of city railway EMU carbody, a refined finite element model of the carbody and a rigid-flexible coupling dynamics model are established. According to vibration isolation design principle, an elastic suspended device is designed corresponding to transformer and air-source device under carbody, and the correspondent installation frequency and dynamic stiffness are analyzed respectively, as well as the impact of the elastic suspended device on passenger riding comfort. Under working condition of train running at highest speed of 140 km/h, in different designs of elastic suspension frequency, the total amount of vehicle floor vibration acceleration is calculated based on ISO 2631 index. Results show that the elastic suspended device can effectively reduce the vehicle elastic vibration, improving the ride comfort.