Abstract On the basis of the BDS-3 precision orbit and clock products released by Xi’an Research Institute of Surveying and Mapping, we study the satellite differential code bias(DCB) correction model of B1C-B2a dual-frequency combination, and analyze the stability of DCB products released by the Chinese Academy of Sciences. The observation data of 7 days from 10 MGEX stations are used to compare and analyze the BDS-3 precise point positioning accuracy of B1I-B3I and B1C-B2a dual-frequency combination under the undifferenced and uncombined model and ionospheric-free combination model. The results show that the BDS-3 static positioning accuracy is better than 2.0 cm horizontally and 2.5 cm vertically, and the convergence time is about 31 min. The simulated dynamic positioning accuracy is better than 3.4 cm horizontally and 4.1 cm vertically, and the convergence time is about 60 min. The B1I-B3I and B1C-B2a dual-frequency combination positioning accuracy is nearly equal and the convergence time is close. Both can be used for BDS precise point positioning.