Abstract Considering the high stability of high-performance hydrogen clocks and the strong correlation between clock offset series epochs, the receiver clock offset with additional prior information constraint is tested for precise point positioning(PPP) timing. The results based on B1C/B2b combination of BDS-3 show that compared to traditional timing models, the precision timing models with additional prior information have higher timing performance, especially for the short-term stability which has an improvement up to 60%. In addition, the PPP accuracy of B1I/B3I and B1C/B2b combinations of BDS-3 is basically equivalent, which can achieve positioning accuracy better than 0.5 cm and about 2 cm in horizontal and vertical direction, respectively. Owing to the better observation data quality of B1C/B2b, the positioning accuracy is improved by 13.8% compared to the B1I/B3I combination.