Abstract: The 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 of 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 EdgeTech 6205 S2 based on multi-phase echo sounder (MPES), systematically describes its technical principle, performance parameters and system composition, and taking a submarine oil pipeline survey project as an example, the performance and technical advantages of BSSS in nearshore marine engineering are analyzed. The results show that the MPES sonar not only maintains the advantages of high-resolution sidescan image, but also realizes the function of wide coverage and high-precision sounding. The three-dimensional bathymetric and dual frequency sidescan sonar registration images obtained synchronously can be used to accurately identify and locate the main submarine geomorphic features in the submarine pipeline survey area, such as reefs, backfilled trenches, exposed pipelines, anchor chain trenches, etc., which has reference significance for the selection of nearshore marine engineering survey methods.