Abstract:Ionospheric grid provides information about space weather, gives empirical forecast models, and helps improve accuracy of user navigation and positioning. Taking into account the wide application of ionospheric grid, based on measured data of some IGS stations, this paper assesses the inner accuracy of ionospheric grid products at five centers and two integrated analysis centers (IGS and iGMAS) worldwide.The results show that there are different accuracy of different types of GIM products in different organizations and different ranges.