In order to study the aerodynamic characteristics of high-speed train (HST) running at part-cut and part-fill railway transition section under crosswind, 3-group HST was taken as the study object. Based on the SST k-ω two-way turbulence equations, FLUENT was used to study the aerodynamic characteristics of HST running at the speeds of 250, 300 km/h and 350 km/h, under crosswind action with speeds of 15, 20 km/h and 25 m/s, respectively. The study results showed that, with the same wind speed and same vehicle speed, the head-vehicle suffered maximum lateral force and overturning moment, and the middle-vehicle suffered maximum aerodynamic lift; with the increase of vehicle speed and wind speed, the aerodynamic characteristics of trains in- creased; the influence of wind speed on HST’s lateral force and the overturning moment is greater than that of vehicle speed.