To solve the problem of line path control when the 2-DOF articulated vehicle surmounting obstacle, the dynamical model is developed, the angle velocity φ_r of the rear body rotates about z axis, the velocity y_r along y axis and yaw velocity θ₁ of the front body relative to the rear body are chosen as controlled variables, and the error kinematic model of the vehicle is developed, the stability and controllability of system are analyzed. Because the net moment provided by the hydraulic steering mechanism has the amplitude, an anti saturation controller is designed by backstepping method to suppress the output saturation of the hydraulic steering mechanism in the yawing control. After putting the anti-saturation algorithm in the error control system, it is shown that the error in y direction i converges to 0 in 5 seconds, also the angle θ₁ and φ_r converge to 0. The tracking path of vehicle is beeline. The anti-saturation algorithm is verified to eliminate the yawing error effectively by the simulation. And the curve of net moment provided by the hydraulic steering mechanism is calculated in the process of the yawing control.