Abstract:The theory and algorithms of multi-GNSS precise point positioning(PPP) are studied and the convergence time and positioning precision are also analyzed in this article. We use observations from GPS, GLONASS, Beidou and Galileo and the MGEX precise ephemeris and clock from GFZ. The results show that, in static PPP, the convergence speed of Beidou is slow and the positioning accuracy of Beidou is about 5 cm in horizontal, 8 cm in vertical. The convergence speed of G/R/C/E combined PPP is faster than any single system and the positioning accuracy is close to GPS. In kinematic PPP, the average convergence time of Beidou is 110 min or more and the positioning accuracy of Beidou is about 8 cm in horizontal, 16 cm in vertical. The convergence speed of G/R/C/E combined PPP is also the fastest, whereas the positioning accuracy is not significantly improved compared to GPS. Under the circumstances of higher cut-off elevation, the positioning errors of GPS are larger than multi-GNSS, since multi-GNSS can observe more satellites than GPS.