This paper introduced the basic principle of GPS-RTK three-dimensional multi-beam sounding survey of HZMB-CORS,and the key setting and operation in sounding data acquisition software QINSy,as well as the exportation and computation method of GPS-RTK tide in data post-processing software Caris.Contrasting with traditional multi-beam bathymetric survey method with tide gauge by sounding data collection experiment at site,we analyze the precision of GPS-RTK tide collected and the internally coincident precision as well as externally coincident precision.The result shows that GPS-RTK three-dimensional multi-beam sounding survey method has obviously improved working efficiency and reduced the work cost,and effectively improved the precision of multi-beam sounding survey and the stability of sounding data.