Abstract: When the wake of ships is measured with multi-beam sonar sitting on the sea bottom, there is serious sidelobe interference in the sonar image due to energy leakage from the sidelobes, caused by strong reflection echoes on the sea surface. This interference creates a "bright ring" effect in the wake image, which disturbs data analysis. In order to study the acoustic characteristics of the wake, a mathematical morphological image processing algorithm combined with image Hough transform and contour tracking technology is proposed, which can effectively separate the wake target from environmental interference. Data simulation demonstrates that this algorithm can successfully identify and eliminate "bright ring" sidelobe interference and reduce scatter image noise while accurately extracting the boundary contour of the wake target. It has practical application value in engineering.