The features and advantages of iGPS system applied in navigation and GPS augmentation were analyzed in this paper. Three conclusions were obtained by analyzing the iGPS system architecture, time synchronization and Doppler positioning solution. Firstly, reduce the dependence of the ground site to increase the flexibility of the system architecture. Then, in the work system, the independent signal can be used broadcast or the high orbit satellite augmented signals can be transmitted to increase the anti-jamming capability of the system. Finally, navigation terminals can use Doppler positioning to reduce the number of visible satellites.