Abstract: In MEMS_SINS/GPS integrated navigation system, the output of GPS often contains fault signals. For this problem, a fault-tolerant filtering algorithm is proposed. The possible faults contained in GPS are augmented to the state vector, and the fault-toleration could be achieved by estimating the faults on line and compensating the system. The new algorithm was verified off line with the experimental data from MEMS_SINS/GPS integrated navigation system. The results show that the effect of GPS fault signal is significantly reduced so that the navigation system could still work in the normal range during the time.