In　this　paper,　the　problem　of　line　optimization　existing　in　the　practical　application　of　multi-beam　sonar-sounding　technology　is　studied.　Firstly,　by　analyzing　the　working　principle　of　multi-beam　sonar,　the　multi-beam　coverage　width　model　and　the　overlap　rate　model　between　adjacent　strips　are　established　considering　the　slope　of　seabed　terrain.　Then,　a　more　general　parameterized　multi-beam　coverage　width　formula　with　an　adjustable　azimuth　angle　of　the　line　is　derived　under　three-dimensional　space　coordinates.　Then,　the　minimum　total　line　length　is　defined　as　the　objective　function,　and　the　constraint　conditions　of　overlap　rate　and　complete　coverage　are　added　to　establish　the　mathematical　model　of　line　planning.　Then,　an　iterative　algorithm　is　designed　to　quickly　determine　the　line　spacing,　and　an　improved　particle　swarm　optimization　algorithm,　including　a　trigonometric　function　change　learning　factor,　is　used　to　search　for　the　optimal　line　layout.　Finally,　the　simulation　results　show　that　the　optimized　scheme　can　reduce　the　total　line　length　by　2%　compared　with　the　unoptimized　line　layout,　which　verifies　the　effectiveness　of　the　established　model　and　algorithm.　This　study　provides　a　theoretical　basis　for　navigation　planning　and　shipboard　system　optimization　of　multi-beam　sonar　survey.　Subsequent　work　taking　into　account　the　influence　of　complex　sea　conditions,　efforts　were　made　to　expand　the　model＇s　applicability.　©　Published　under　licence　by　IOP　Publishing　Ltd.