Aiming at the actuator failure in the work of unmanned underwater vehicle (UUV), an adaptive robust fault-tolerant control method based on finite time disturbance observer (FTDO) and improved model was proposed under system uncertainty and external interference. On the one hand, the external environmental interference could be estimated by FTDO in a limited time. On the other hand, sliding mode control and the universal approximation characteristics of radial basis function neyral network (RBF) were used to establish input compensation with actuator fault. Among them, the input saturation caused by system uncertainty was solved by the improved model, which improved the stability and robustness. Secondly, a new type of double-power approximation law was adopted to make the sliding modulus converge to the steady-state error range in a shorter time. The simulation and pool experimental results show that the proposed method has a better fault tolerance effect than the sliding mode control.