Natural wind will affect the vehicle's stability when it is running at high speed. Natural wind can be decomposed into two components to the vehicle body in parallel and vertical directions. The velocity of parallel direction component can be superimposed on the train's speed directly, while the velocity of vertical direction component is referred to as cross-wind. It makes the train to withstand lateral movement and roll movement. Cross-wind has a great influence on the lift, lateral force and heeling movement of the vehicle. Heeling movement plays a major role on the stability of moving vehicle. When the vehicle moves out of the tunnel and meets a strong cross-wind or when the vehicle is running on the viaduct, elevated railroad, high embankment areas, hilly canyons, mountain air traffic zone and multi-curve road, and meets a strong cross-wind, it would lead to an accident of overturn or derail. Steel windbreak can effectively prevent cross-wind and reduce its defect on traffic to minimum.