This article covers a method to estimate the sideslip angle and the max tire-road friction coefficient simultaneously via inertial measurement unit, steering system and stereo camera equipped in the front of the autonomous vehicle. First the steering system model is constructed as two order system to estimate the kingpin torque. And then the estimation algorithm feedback gain is designed. Finally the stability of the estimation algorithm is proved through Lyapunov method. Simulation results show the proposed algorithm’s performance is better than extend Kalman filter algorithm.