This paper aims to measure the seabed depth using a multibeam survey line scheme and analyze its performance in a real sea area. The multibeam depth measurement system can send and receive multiple sound waves in a plane perpendicular to the survey line, achieving high accuracy, resolution and efficiency. This paper builds a mathematical model, using geometric analysis, vector algebra, iteration, traversal and other methods, to determine the multibeam depth measurement coverage width model, and find the variable relationship of survey line length, spacing, overlap rate, slope, etc. Using a rectangular seabed slope as an example1, this paper first covers the sea area with parallel survey lines, and then applies the genetic algorithm to calculate the coverage width of different survey line positions, and derive the shortest, full-coverage, overlap rate 10%~20% survey line combination.