Abstract: If a multi-beam sounding system is installed in a conventional way (vertical), it is difficult to collect data from hydraulic structures in shallow water areas due to the limitation of the beam opening angle, and the reliability of the edge beam accuracy is gradually decreasing.Therefore, combined with the working principle and characteristics of multi-beam sounding system, a new installation scheme of multi-beam sounding system was proposed, that is, a conversion flange was made, with its upper end installed in parallel with the installation rod, and the lower end connected with the transducer in a tilted way.In addition, field tests were carried out in the spillway holes, longitudinal cofferdam and the junction areas of the Three Gorges Dam.The data acquisition accuracy of four modes of conventional measurement with vertical installation, high-density measurement with vertical installation, conventional measurement with inclined installation and high-density measurement with inclined installation were analyzed.The results show that under the condition of keeping the same distance from the scanned hydraulic structure, the absolute accuracy, relative accuracy, relative point cloud density and relative shallowest water depth of the results obtained by the new transducer tilt installation mode were 0.092 m, 0.068 m, 9.56 m² and 2.41 m respectively.On the premise of ensuring the measurement accuracy, the inclined installation can obtain more comprehensive scanning data.To a certain extent, it eliminates the disadvantage that the vertical installation must be as close as possible to the hydraulic structure to obtain more detailed scanning data, which can greatly ensure the safety of personnel, ships and equipment.The high-density measurement mode can more effectively improve the density of measurement points, and the accuracy of the results is more reliable.The relevant results can be used for safety monitoring of underwater parts of similar hydropower projects.