Abstract: This paper analyzes the decoupling controller and sensor system of an Autonomous Underwater Vehicle(AUV),and proposes a fault-tolerant control(also called substituting control) strategy based on the ideas of replacing the fault sensor outputs by the sliding-mode observer outputs.For the irrecoverable sensor faults,this strategy minimizes its damage to the AUV.For the jumping faults of sensors,substituting control is used during jumping.The simulation result proves the validity of this strategy.