Abstract: At present, the aerodynamic force is only placed at the center of the wind pressure in the high-speed driving aerodynamic lift study of a vehicle, so it can not reflect reliably the real force and body dynamics of the running vehicle. In this paper, the driving stability of a vehicle in use is studied after its aerodynamic lift is decomposed to front and rear axles. Through the calculation formula of front and rear axles lift, the HD-2 wind tunnel test data are processed and the front and rear axles lift of the vehicle is obtained. Then the lift is forced on the vehicle multi-body dynamics model and the stability of the vehicle is analyzed according to the three indicators of lateral displacement, lateral acceleration and yaw velocity. The results show that after the aerodynamic lift is decomposed to the front and rear axles of the vehicle, the dynamic performance of the vehicle becomes worse in the late period of lane change condition; that the body dynamics lag obviously in the obstacle avoidance conditions; that under the steady-state steering condition steering of the vehicle is insufficient and the turning radius is increased. The maximum value of the lateral acceleration is decreased by 0.367 5 m/s² and the maximum value of the yaw velocity is reduced by 1.67（°）/s.