To address the problem of robust position tracking of underactuated autonomous underwater vehicles(AUVs) with parameter uncertainties and external disturbances in the horizontal plane,a robust position tracking controller is presented based on the Lyapunov stability theory by using backstepping technique.To compensate the uncertainties,a sliding mode control scheme was proposed.The desired trajectory was chosen as a sinusoidal curve.Simulation results are presented for the underactuated AUV systems with parameter uncertainties and external disturbances to illustrate the effectiveness and robustness of the proposed control schemes.