Abstract: The construction of China’s BeiDou-3 Navigation Satellite System (BDS-3) has been basically completed. Therefore, full use of the current BDS-3 satellite for precise point positioning (PPP) time transfer requires urgent research. This article analyzes BDS-3 PPP time transfer in two aspects. 1) BeiDou-2 Navigation Satellite System (BDS-2), BDS-3 and BDS-2+BDS-3 PPP time transfer. 2) Clock model constrained BDS-3 PPP time transfer. The results show that the root mean squares (RMS) values of smoothed residual value obtained by BDS-3 and BDS-2+BDS-3 PPP can be reduced by 34.5% and 38.23%, the frequency stability of 960 s is increased by 35.81% and 37.75% respectively, compared with BDS-2 PPP; compared with the traditional white noise model, the RMS values of the smoothed residual obtained by BDS-3 and BDS-2+BDS-3 PPP time transfer with the clock model is reduced by 65.17% and 74.42%; in addition, frequency stability can be increased up to 80%.