A　mega-gear　positioning　method　based　on　laser　tracker　multi-station　measurement　was　developed　to　improve　the　positioning　accuracy　of　a　mega-gear　measuring　system　based　on　laser　tracker　and　to　ensure　the　positional　and　attitude　relation　between　measuring　instruments　and　a　gear.　The　redundant　data　provided　by　laser　tracker　multi-station　measurement　were　used　to　solve　the　optimally　collinear　equation　between　two　points　and　to　establish　a　multi-station　measurement　model　based　on　laser　tracker.　Then,　the　singular　value　decomposition　was　used　to　correct　the　conditional　number　of　analytical　matrix　in　the　multi-station　measurement　model.　Experimental　results　show　that　the　standard　deviation　mean　of　the　distance　between　different　station　points　obtained　by　the　multi-station　measurement　mode　is　0.008　mm,　which　is　much　less　than　that　(0.024　mm)　measured　by　directly　measurement　method　at　different　stations.　These　data　mean　that　the　multi-station　measurement　model　has　a　high　control　ability　for　measuring　precision.　The　research　improves　3D　measuring　precision　of　gear　positioning　and　provides　a　reliable　data　source　for　establishing　gear　coordinate　models　of　the　mega-gear　measuring　system　based　on　laser　tracker.