Abstract: Double-front-axle steering mechanism was often used in four-axle vehicle. By adding electro-hydraulic power steering system to the third and the forth axles, it easily becomes an all-wheel steering vehicle. The change which needs the center line of steering must move from the center of the third axle and the forth axle to the middle between the second axle and the third axle. The research shows that this move has less effect on the characteristic of steering. Based this point, a controller was designed to reduce the radius of steering and reduce the rub of tire. Moreover, in order to diminish the fishtailing of rear axle tires, a constant delay time was applied to the output of the controller. All simulation results show that the controller can improve the flexibility of four-axle vehicle and restrain the fishtailing phenomenon effectively.