Due to the vertical installation of conventional multi-beam systems,it is impossible to accurately measure the special underwater topography such as coastal waters,docks,breakwaters,spurs,islands and reefs.In response to this problem,technical research on multi-beam tilt installation and calibration is carried out.The method of multi-beam tilt installation is used to increase the number of beams on the relevant side,and the measurement can reach the position of the waterline,so the accuracy of the water depth results can meet the specifications and engineering requirements.The whole coverage survey of underwater special topography is realized,which can provide technical support for the integrated model of water and underwater,and can be widely used in underwater detection engineering.