Abstract: While multi-Global Navigation Satellite System (GNSS) observation make it possible for a better performance of ionospheric model for Space Based Augmentation System (SBAS), the potential improvement depends on various factors. The paper analyzes the availability of ionospheric grid model for SBAS covering China and around areas under multi-GNSS scenarios. The results show that the covering area of grid model could be extended with multi-GNSS measurements. But for southern China, where equatorial ionolization anomaly (EIA) exists, the performance improves marginally as the increased observations cannot counter effectively the EIA’s serious impacts on grid model. In northern China, the ionosphere varies smoothly and multi-GNSS observations are helpful to reduce the number of sites while maintains the system performance.