In view of the fact that there are few network RTK tests under different satellite combinations in the canyon reach，this paper tests the positioning performance and accuracy of the mobile station under the BDS/GPS/GLONASS combination between the Three Gorges Dam and the Gezhouba Dam.Six observation modes are adopted to test positioning service timeliness，spatial availability and positioning accuracy.The results show that the BDS network RTK of domestic GNSS equipment meets the specification requirements，the fixed solution ratio is 98.1%，and the positioning accuracy of 0.02 m level and 0.05 m elevation can be achieved，which are better than GPS to a certain extent.BDS and BDS/GLONASS dual-system network RTK can still provide high-precision positioning services when GPS signals are missing or not used.Combined positioning can make up for the shortcomings of a single system，and the fusion system has different degrees of improvement compared with each single system.BDS/GPS/GLONASS and BDS/GPS are optimal in terms of positioning service timeliness，spatial availability test and positioning accuracy.