Abstract: A new method of analyzing the crosswind stability of high-speed trains is proposed based on reliability theory, which can be the effective assessment of operational safety reliability of high-speed trains under stochastic crosswinds. Firstly, the fluctuating winds of a moving point shifting with high-speed trains are calculated in this paper based on Cooper theory and harmonic superposition method, and the method of the unsteady aerodynamic loads of high-speed trains under stochastic crosswind winds are presented. The standard deviation of the aerodynamic load coefficients varying with the slip angles are obtained by numerical simulation. Then the vehicle system dynamics model of high-speed trains is established, and the result computed by the model in this paper is compared with the test data to verify the correctness of the model. Finally, the stochastic winds, side fore coefficient, lift force coefficient, roll moment coefficient, yaw moment coefficient and pitch moment coefficient are dealt with as basic random variables, and the operational safety reliability and reliability sensitivity of high-speed trains under stochastic winds are calculated in this paper. This finally leads to the probabilistic characteristic wind curve. The results show that, the probability of failure increases as the vehicle speed or wind speed increases. The side force coefficient and roll moment coefficient cause the greatest impact on the operational safety of high-speed trains. Thus, when assessing the crosswind stability of high-speed trains, special attention should be paid to the variation of these two parameters. The operational safety domain computed by the traditional deterministic method is too conservative, and a more reasonable safety domain curve can be obtained using the method based on the reliability theory.