Through the comparison and analysis of three numerical simulation methods, the optimal simulation scheme was obtained. Therefore, the separation vortices method was used to study the aerodynamic characteristics of Ahmed model, and the influence of different side wind angles on the distribution law of vorticity, turbulence intensity, pressure and streamline of blunt body wake was analyzed. The variation characteristics of force and moment coefficient were obtained, and the comprehensive formula of tail inclination angle changing with side wind angle was summarized. The results show that the influence of the side wind angle on the characteristic parameters of the blunt body wake is not monotonous, and the rear vorticity of the blunt body is the largest when the side wind angle is 30°. The inclination angle and aerodynamic coefficient of the wake of the blunt body increase with the increase of the side wind angle. Back windward side pressure and average head speed of the blunt body also reach maximum values at a side wind angle of 50°. The conclusions provide some basis for the safety and stability of vehicle operation under complex transverse inflow conditions.