Abstract: Ionospheric delay resulted from radio signals traveling in ionosphere is the largest source of errors for satellite-based positioning and navigation system. A new algorithm of ionospheric delay correction was proposed in the course of taking the task of ``BD-2'' subsystem, and tested using 6 dual-frequency GPS stations' observational data of China crust deformation monitoring network. Further, comparison of TEC (Total Electron Content) errors derived from the proposed algorithm to the ones from ionospheric grid algorithm was considered. The results show that the gauged error of TEC is about 0.5 meter for the users located in middle latitude, but the error increases and reaches one meter for the low latitude users. The proposed method and ionospheric grid model can provide almost performance for the view of ionospheric delay correction. It is concluded that the proposed method is valid and practicable for the future satellite-based augmentation system of China.