Abstract: Sudden gusts are likely to threaten the running safety of high-speed trains due to the instantaneous change of wind speed in a short time. Based on the theory of one-dimensional multivariable non-stationary stacastic process, the fluctuating wind fields are simulated for the spatially correlated time-varying gusts. With the help of multi-body dynamics software SIMPACK and finite element software ANSYS, a rigid-flexible coupling model for the interaction between rigid trains with 42-degree-of-freedoms and flexible track-bridge is established. Considering the influence of the time-varying crosswind gusts, a relatively compelete wind-vehicle-track-bridge coupling dynamics analysis system is formed based on the rigid-flex coupling method. Taking a long-span arch bridge as engineering case, the effects of time-varying gusts on the dynamic responses of train and bridge are analyzed with focus on the driving safety of trains under the influence of gusts with different vehicle speeds and wind velocities. The results indicate that the gusts have an important influence on the dynamic responses of bridges and vehicles. Under the same conditions, the lateral displacements of the main span increase up to 200% considering the influence of gusts while the wheel load reduction rate and derailment coefficient of the vehicle are increased by nearly 30% compared with no gusts. When the wind speed is greater than 25 m/s and the vehicle speed is greater than 80 km/h, the wheel load reduction rate will exceed the safety limit, indicating that the vehicle may derail.