As the speed of train increases, flow-induced vibration of trains passing through tunnels has become a subject of discussion, to investigate this phenomenon, a simplified geometric model and a vehicle dynamics model of a high-speed train traveling through a tunnel were built. To analyze the unsteady three-dimensional flow around the train, the 3-D, transient, viscous, compressible Reynolds-averaged Navier-Stokes equations combined with the k- two-equation turbulence model were solved with the finite volume method. The motion of the train was carried out using the technique of sliding grid method. The dynamics response of the train was obtained by means of the computational multi-body dynamics calculation. Meanwhile the running safety and riding comfort of the train were analyzed. With the numerical simulation, the variation of aerodynamic forces was obtained. The research founds that, vibration of the train increases drastically during it passing through a tunnel. The running safety and riding quality of the train are reduced greatly but they are in the safe range.