Abstract: In order to validate the applicability of GNSS 3D bathymetric surveying technology relying on single BeiDou Navigation Satellite System(BDS) positioning, a water depth measurement and analysis were conducted in the natural river reach from Zhutuo to Yibin in the upper Changjiang River.The measurement results were contrasted with those obtained from the traditional water-level sounding technique based on single Beidou positioning.The results indicated that in the RTK accuracy analysis, for the upper Changjiang River reach, 100% of the data had a horizontal comparison limit error within 10 cm, and 98.3% of the data had an elevation comparison limit error within 5 cm.This demonstrated that when measuring in this river reach, the single BDS positioning system offers stable positioning and relatively high accuracy.Regarding the analysis of the mean square error of the water surface elevation, the mean square error of the water surface elevation at each measurement point was less than 0.08 m.This showed that the satellite signal reception in this river reach was in good condition and stable at different times.In the comparative analysis of the cross-sectional erosion and deposition between two measurement campaigns in this river reach, the deposition volume calculated from the data of GNSS 3D bathymetric surveying technology was 22.266 million m³, while the deposition volume calculated from the data of the traditional water-level observation method was 6.025 million m³.Integrating the analysis of the water surface elevation, the data of GNSS 3D bathymetric surveying technology was more reliable.Consequently, the GNSS 3D bathymetric surveying technology exhibits a higher applicability in the natural river reach of the upper Changjiang River compared to the traditional water-level sounding technology.