As　a　reliable　and　high-precision　three-dimensional　(3D)　vision　method,　line　laser　structured　light　vision　has　been　widely　used　in　the　engineering　field.　However,　to　obtain　overall　3D　shape　of　target　to　be　measured,　scanning　mechanisms　need　to　be　added.　Multi-line　laser　structured　light　vision　can　obtain　multi-line　array　3D　shape　of　workpiece　without　scanning;　however,　the　encoding　of　multi-line　lasers　is　a　difficult　task.　This　paper　proposes　a　composite　vision　system,　which　is　composed　of　time-of-flight(TOF)　camera,　color　camera　and　vertical　cross　multi-line　laser　structured　light.　Color　camera　and　multi-line　laser　form　a　multi-line　array　3D　vision　system,　while　the　coded　signal　of　multi-line　laser　stripes　is　provided　by　TOF　camera　and　corresponding　coding　algorithm　is　also　proposed　in　this　paper.　Based　on　this　system,　automatic　positioning　of　welding　seam　is　realized　by　registration　of　CAD　data　and　multi-line　laser　3D　data.　The　registration　is　divided　into　two　steps,　which　are　coarse　registration　and　precise　registration.　Coarse　registration　is　performed　by　using　CAD　point　cloud　data　and　original　point　cloud　data　of　multi-line　laser;　while　precise　registration　is　performed　with　CAD　welding　seam　point　cloud　data　and　welding　seam　point　cloud　data　of　multi-line　laser.　This　paper　also　analyzes　accuracy　of　vision　system　based　on　constructing　structured　light　vision　model.　The　measurement　accuracy　of　vision　system　in　x,　y　and　z　directions　is　0.25,　0.06　and　0.29　mm　respectively.　This　composite　vision　system　can　realize　precise　positioning　of　target　within　a　single　exposure　time,　which　provides　possibility　for　positioning　under　movement.　©　2022　Elsevier　GmbH