Federated filter was an important method to estimate high-precision navigation parameters based on “SINS/GPS/CNS”. A no-feedback federated filter with UD_UKF algorithm was designed in the paper, a three-time amendment scheme to correct navigation parameters was designed at the same time and the mathematical model of SINS/GPS/CNS was established in launch inertial coordinate system too. The paper discussed the simulation conditions and a lot of simulations were carried out to compare 2 aspects: (1)the performance between four navigation mode, which respectively is SINS, SINS/GPS, SINS/CNS, SINS/GPS/CNS;(2)the estimate precision of federated filter and that of centralized Kalman filter. The results of simulation showed that the designed federated filter and amendment scheme based on SINS/GPS/CNS had high estimate precision and led to gain high hitting precision of ballistic missile, that is to say position errors were less than 20 meter and velocity errors were less than 0.1m/s in simulation.