Abstract: In order to solve the problem that network real-time kinematic (RTK) communication signals are easy to be interrupted in the remote sea and desert, a switching technology of RTK/B2b-PPP fusion based on BeiDou-3 Navigation Satellite System (BDS-3)/GPS is proposed, which makes full use of the characteristics of fast convergence and high positioning accuracy of network RTK and wide coverage,single station positioning of B2b-PPP. The high-precision position coordinates obtained by network RTK are used as priori information and integrated with B2b-PPP to assist B2b-PPP converge fast. The results show that the positioning accuracy of RTK fixed solution and B2b-PPP fusion is 2.57 cm, 0.90 cm and 2.83 cm in the east (E), north (N) and up (U) directions, respectively, which is much higher than that of independent B2b-PPP positioning. In addition, after the fusion of RTK fixed solution and B2b-PPP for 1 s, it can help the instantaneous convergence of B2b-PPP. After the interruption of RTK, the initial accuracy reaches the level of cm, and gradually transitions to the independent positioning accuracy level of B2b-PPP after 0.5 h, indicating that B2b-PPP can be used as an effective means to supplement the network RTK. Can effectively maintain high precision positioning level.