Abstract: Aiming at the trajectory tracking problem of unmanned vehicle, a coordinated control strategy of front-wheel steering angle and yaw stability was proposed for unmanned vehicle based on state estimation. Firstly, a vehicle trajectory tracking model was established, and a trajectory tracking controller was designed with the model predictive control algorithm to obtain the front-wheel steering angle required of tracking reference trajectory in real time. And then, according to the vehicle model, a method of front-wheel steering angle estimation based on unknown input observer was designed and the estimation result was used as the input of front-wheel steering angle tracking control. Based on the nonsingular terminal sliding mode control, a front-wheel steering angle tracking method was designed, and the trajectory tracking was realized by the torque control of steering motor. At the same time, a vehicle yaw stability controller was designed to ensure the vehicle yaw stability by controlling the yaw rate tracking error. Finally, a CarSim-Simulink co-simulation model was established and used for simulation test. The results show that, the unknown input observer has a better effect on front-wheel steering angle estimation, which provides a reliable information source for vehicle coordinated control. And the coordinated control strategy can ensure the vehicle yaw stability and complete the vehicle trajectory tracking at the same time.