Abstract: The dynamic responses of trains running on cable-stayed bridges during earthquake are studied.A model of coupled train-bridge system is established,with seismic waves and track irregularities as the excitations.A computer simulation programme is developed to serve the purpose.A case study is performed in which a rail-cum-road cable-stayed bridge that will cross the Yangtze River in China is examined.By inputting the typical seismic waves to the train-bridge system,the whole history of the train running through the bridge is simulated and the dynamic responses of the bridge and the vehicles are calculated.Results show that seismic excitations have significant effects on the running safety of the train vehicles on the cable-stayed bridge.