The　integrated　manufacturing　of　aerospace　composite　cryogenic　tanks　is　crucial　for　enhancing　payload　efficiency,　reducing　costs,　and　leading　the　aerospace　industry　upgrade.　Composite　segmented　tool,　which　balances　internal　support　and　mold　surface,　must　not　only　meet　the　requirements　of　disassembly　and　demolding　but　also　ensure　sufficient　stiffness　without　deformation　under　loads　like　winding　tension　and　curing　shrinkage　during　tank　formation.　This　article　addresses　the　challenge　faced　by　composite　tool　with　uniformly　thick　ply　stacking　schemes,　where　the　weight　increases　significantly　with　the　rocket　body　diameter,　rendering　functions　such　as　disassembly　and　demolding　unfeasible.　A　global-local　optimization　approach　aimed　at　achieving　variable-thickness　ply　stacking　designs　for　composite　tooling　was　proposed.　Starting　with　a　defined　segmented　tool　design　for　the　phi　3.35　m　tank,　models　for　calculating　winding　tension　under　complex　service　conditions　and　finite　element　models　for　curing　shrinkage　were　established.　Optimization　of　ply　shapes,　dimensions,　and　sequences　using　OptiStruct　was　conducted,　which　achieved　a　weight　reduction　of　34.48%　while　ensuring　that　deformations　under　loading　met　design　standards.　Subsequently,　the　engineering　trials　for　the　composite　melon　petal　and　wallboard　corresponding　to　the　phi　600　mm　tank　were　conducted　based　on　the　optimized　scheme.　The　maximum　deformations　for　the　two　components　were　0.43　mm　and　0.15　mm,　respectively,　meeting　the　manufacturing　requirements　for　engineering　applications.　The　results　provide　a　lightweight,　high-stiffness,　and　detachable　tool　design　scheme　for　achieving　the　integrated　manufacturing　of　extra-large　(phi　10　m)　composite　tanks.Highlights　The　external　load　was　analyzed　through　theoretical　and　simulation　approaches.　The　weight　of　composite　tool　was　significantly　reduced　after　optimization.　The　engineering　prototypes　of　the　segmented　tools　were　achieved.　Structure　design　and　optimization　for　composite　tool　of　aerospace　cryogenic　tank.　image