Abstract: The dynamic performance of high-speed trains is significantly influenced by sudden changes in aerodynamic loads (ADLs) when exiting a tunnel in a windy environment. Focusing on a double-track tunnel under construction in a mountain railway, we established an aerodynamic model involving a train exiting the tunnel, and verified it in the FLUENT environment. Overset mesh technology was adopted to characterize the train's movement. The flow field involving the train, tunnel, and crosswinds was simulated using the Reynolds-averaged turbulence model. Then, we built a comprehensive train-track coupled dynamic model considering the influences of ADLs, to investigate the vehicles' dynamic responses. The aerodynamics and dynamic behaviors of the train when affected by crosswinds with different velocities and directions are analyzed and discussed. The results show that the near-wall side crosswind leads to sharper variations in ADLs than the far-wall side crosswind. The leading vehicle suffers from severer ADLs than other vehicles, which worsens the wheel-rail interaction and causes low-frequency vibration of the car body. When the crosswind velocity exceeds 20 m/s, significant wheel-rail impacts occur, and running safety of the train worsens rapidly.