Abstract: A bathymetric sidescan sonar system (BSSS) can synchronously collect high-resolution seabed terrain data and geomorphic image information by integrating bathymetric and sidescan functions, effectively improving the operation efficiency in nearshore seabed topography and geomorphology integrated survey. Aiming at the shortcomings of traditional BSSS, such as low sounding accuracy, serious noise interference and inherent detection blind area, this paper introduces the Edgetech 6205 S2 System based on multi-phase echo sounder (MPES), systematically describes its technical principle, performance parameters and system composition. Taking a submarine oil pipeline survey project as an example, the performance and technical advantages of BSSS in nearshore marine engineering were analyzed. Results show that the MPES sonar could not only maintain the advantages of high-resolution sidescan image, but also realize the function of wide coverage and high-precision sounding. The three-dimensional bathymetric and dual frequency sidescan sonar registration images obtained synchronously were used, by which the main submarine geomorphic features in the submarine pipeline survey area, such as reefs, backfilled trenches, exposed pipelines, and anchor chain trenches were accurately located. This study provided an good reference for the selection of nearshore marine engineering survey methods.