The performance of the Chinese BeiDou navigation satellite system (BDS) for navigation and positioning has been enhanced gradually, which benefits from the improvement of the availability and distribution of monitoring stations. The aim of this paper is to assess positioning precision of GPS and BDS based on the existing high-precision positioning mode. Results showed that the overall accuracy of double differential solution would be better than the un-differential precise point positioning (PPP) solution, i.e., the accuracy of double differential solution could reach about millimetre-level while the un-differential PPP accuracy could be only about centimetre-level. The accuracy of the BDS/GPS combination solution could be roughly equivalent to that of the GPS individual solution, both of which would be superior to that of the single BDS solution with about centimetre-level. After the orbit-normal and yaw-steering correction is adopted, the positioning accuracy of BDS could be better than 5cm. Moreover, compared with the conventional PPP solution, PPP network solution by double-difference ambiguity fixed and Uncalibrated Phase Delay (UPD) ambiguity fixed would have higher accuracy and converge faster. In contrast with the double-difference precise baseline solution, the UPD ambiguity fixed network solution with faster convergence speed could have the same accuracy and could also ensure the rigor of the whole network solution, providing a new rapid monitoring technology with high precision for the GNSS station network.