Abstract: With the action of cross wind, the existence of bridge tower results in a significant change in the distribution of wind field above bridge deck. In order to investigate the adverse influence of the change of wind field on the running safety and comfortability of a train, the CFD (computational fluid dynamics) numerical method was used to simulate the wind field above the bridge deck nearby the towers of a long-span suspension bridge. By a wind tunnel test with section model for deck and vehicles, the aerodynamic coefficients of vehicles running along rails with different positions and the bridge were measured respectively. Based on the wind field distribution and the measured aerodynamic coefficients, a self-developed analysis software BANSYS was adopted to conduct a contrast analysis for the dynamic responses of vehicles running through a bridge tower along different rail positions. The research results indicate that the changes of wind field nearby the bridge tower are dramatic to result in a local acceleration effect. And the sudden change of wind field nearby the bridge tower has an obvious influence on the lateral responses of vehicles.