In order to reveal the safety mechanism of higher speed trains on the bridge under crosswind, a highspeed train-bridge aerodynamic model was established using CFD software to calculate the aerodynamic loads on the train and bridge based on fluid dynamics and vehicle dynamics theories. Using the co-simulation technology of multibody dynamics software UM and finite element analysis software Ansys, a high-speed train-trackbridge system dynamic model was developed. The aerodynamic loads on the train and bridge were applied as external excitations and input into the train-track-bridge system dynamics model to simulate the entire operational process of high-speed trains on bridges under crosswind conditions. The study analyzed the impact of wind speed and train speed on the operational safety of higher-speed trains. The results show that under crosswind conditions, the lateral displacement of the train body, lateral wheelset force, vertical wheel-rail force, derailment coefficient, wheel load reduction rate, and lateral displacement at the mid-span of the bridge all increase significantly compared to no-wind conditions. When the wind speed is slower than12 m/s and the train speed is 350~400 km/ h, the safety indicators for train operation remain relatively low, and the lateral displacement at the bridge midspan shows moderate variation. When the wind speed is fast er than 15 m/s and the train speed is between 350~ 420 km/h, the safety indicators of the train increase sharply, especially for trains traveling at speeds above 400 km/h, where the lateral interaction between the wheel and rail becomes more pronounced, resulting in an exponential increase in the lateral displacement at the bridge mid-span. The above research results can provide a theoretical basis and basic data for ensuring the running safety of high-speed trains on bridges under the influence of crosswinds.