Abstract: Suzhou Branch of Jiangsu CORS has built a whole city covering BeiDou ground-based augmentation system framework network.It provides services to regional users based on this framework network. A series of tests were conducted on the stability and limitations of the connection of various source nodes under different environments. The results show that its positioning accuracy can meet the requirements. The plane accuracy is better than 5 cm and the elevation accuracy is better than 10 cm, whether the receiver adopts single star mode, double star mode or three star mode when the satellite is not occluded. In the satellite occlusion case, three star mode advantage is particularly obvious,its initialization time, stability and positioning accuracy are better than the other two modes.