As an important part of coastal industrial facilities, the high-precision and high-efficiency survey of channel bottom terrain of sea water intake channels is of great significance to ensure the safe operation of projects. Compared with traditional marine surveying and mapping technical methods, the multibeam echosounder system presents remarkable advantages in marine surveying and mapping. This paper briefly introduces the working principle and hardware composition of the system. Taking the cooling water intake channel of a power plant in Dongying as the research object, the Haizhuo MS400U echosounder system is adopted to acquire point cloud data of the canal bottom, and a 0.2 m resolution DEM of the canal bottom is established by using ArcGIS to intuitively present the current terrain of the canal bottom. The application results provide reliable data support for canal bottom elevation analysis and dredging calculation.