Abstract: The third-generation of Chinese BeiDou Satellite System (BDS-3) has been providing global service since the end of 2018. In order to evaluate the accuracy of BDS-2 and BDS-3 standard point positioning (SPP) as well as visible satellites and GDOP, 90 days of BDS-2 and BDS-3 data collected from 37 globally distributed International GNSS Service (IGS) Multi-GNSS Experiment network (MGEX) stations was used to perform data analysis. Results show that: 1) The geometry of BDS-3 is significantly improved when compared with that of BDS-2 by analyzing the visible satellites and GDOP. 2) The RMS of BDS-3 SPP error is 1.490, 2.610, 5.238m in the east, north and up directions, which is improved by 58％, 1％, and 24％ respectively when compared with that of BDS-2. 3) The RMS of combined BDS-2／BDS-3 SPP error is 1.45, 2.36, 4.90 m, which is improved by 59％, 11％ 29％ when compared with the BDS-2 results. 4) The RMS of combined BDS-2／BDS-3 SPP error is improved by 3％, 10％, 6％ when compared with the BDS-3 results. We also find that the combination of BDS-2 and BDS-3 weakens the marginal effect of BDS-2 SPP which is related to the geographical longitude.