Abstract: The effects of tropospheric mapping functions on the precise point positioning with ambiguity resolution (PPP-AR) should not be neglected . Real-time data for Wuhan University’s precise orbits, satellite clock biases, earth rotation parameters, and observable-specific signal bias (OSB) products were received through the international GNSS service (IGS) ntrip client mount point OSBC00WHU1. The data were combined with observations from 11 multi-GNSS experiment (MGEX) stations distributed in Australia. The study investigated the effects of four tropospheric mapping functions, including Niel mapping function (NMF), global mapping function (GMF), Vienna mapping function 1 (VMF1), and Vienna mapping function 3 (VMF3) for real-time PPP-AR performance of the BeiDou navigation satellite system (BDS), BDS/GPS, and BDS/GPS/Galileo. The experimental results showed that the four tropospheric mapping functions had minimal effects for real-time PPP-AR performance of BDS, BDS/GPS, and BDS/GPS/Galileo. The use of GMF and VMF3 provided comparable real-time PPP-AR performance, outperforming NMF and VMF1. The average positioning accuracy of BDS real-time PPP-AR in the dynamic and static modes is generally comparable in the east and north directions, both around 1.0 cm. However, there is a significant difference in the average positioning accuracy in the up direction, approximately 3.5 cm and 2.6 cm, respectively. The average positioning accuracy of BDS/GPS/Galileo real-time PPP-AR shows a significant improvement more than BDS, while the improvement more than BDS/GPS is relatively small.