Abstract: To pursue lightweight and high speed, implementing a series of drag reduction measures on the train is of great importance. However, the aerodynamic effects due to such measures can be amplified when the train is in crosswind, making the aerodynamic loads particularly sensitive. To thoroughly investigate the adaptability of different aerodynamic drag reduction strategies for a 400 km/h high-speed train in crosswind, this study employed the improved delayed detached eddy simulation (IDDES) method based on the SST k−ω turbulence model for numerical simulations, complemented by wind tunnel experimental validation. Two common aerodynamic drag reduction strategies, i.e. bogie and pantograph optimizations, were selected to clarify changes in the aerodynamic loads and the surrounding flow evolution. The results indicate that these drag reduction strategies remain highly effective in the crosswind condition, and the total drag was decreased by 66.7% with the bogie optimization and by 20.0% with the pantograph optimization. Compared to the baseline model, after the bogie optimization, the negative pressure on the leeward side of the leading car was significantly enhanced, with the lateral force on the leading car increased by 4.2% and its overturning moment by 3.7%, the lift on the middle car reduced by 7.1% and the overturning moment on the tail car increased by 16.9%. After the pantograph optimization, the vortex development on the leeward side was slower, and the velocity farther from the train surface decreased. Additionally, the high negative pressure region on the leeward sides of the middle and tail cars expanded, resulting in significant changes in the lateral force, with an increase of 39.2% for the middle car and 111.7% for the tail car. Although the optimizations of the bogie and pantograph have shown significant effectiveness in reducing the aerodynamic drag of the train, this improvement may have adverse effects on the aerodynamic performance in the crosswind environment. For operating speeds between 100 km/h and 360 km/h, the critical wind speed of the train is significantly reduced in both optimization strategies, substantially affecting the safe operating range. Therefore, when designing strategies for aerodynamic drag reduction of high-speed trains, it is essential not only to meet the drag reduction requirements, but also to consider the train’s adaptability in crosswind environments to ensures the safe operation of trains.