According to the simulation experiments, the performance and characteristic of CNS/INS integrated navigation are analyzed in this paper. Firstly, the basic theory of celestial navigation is discussed, and the algorithm of CNS/INS integrated navigation is presented. Then, the celestial navigation and inertial navigation simulation models are set up. What’s more, the CNS/INS integrated navigation simulation system is realized. The simulation results show that the accumulative errors of inertial navigation are checked effectively by the CNS/INS integrated navigation, which is benefit to realize the high precision airborne navigation with long-distance and long-endurance.