Multi-sensor integrated navigation system is a typical nonlinear system, a federated UKF algorithm is proposed to improve its filtering accuracy in this paper. Firstly, the standard UKF is simplified on the basis of establishing nonlinear state equation and linear measurement equation of multi-sensor integrated navigation system. Then, based on this simplified UKF, the federated UKF algorithm of multi-sensor integrated navigation system is proposed, the attitude fusion algorithm is designed, and the fault detection function is designed simply in order to verify the fault-tolerant performance of the algorithm. Finally, the GNSS / CNS / SINS multi-sensor integrated navigation system is taken as an example for simulation verification. The simulation results show that the federated UKF algorithm can improve the position and attitude accuracy by 25. 8% and 22. 2% when compared with the federated linear Kalman filter, and inherit the fault-tolerant performance of the federated linear Kalman filter.