To　further　improve　the　mechanical　properties　of　the　support　structure　of　the　offshore　wind　turbine，a　topology　optimization　design　method　is　proposed　by　adjusting　the　leg　distance　to　change　the　design　domain.　A　multi-objective　normalized　weighted　compliance　minimum　optimization　model　is　established　while　the　volume　fraction　and　engineering　manufacturing　constraints　are　imposed　as　constraints.　The　variations　of　optimized　topologies　are　analyzed.　Based　on　IEC　61400-3　specification　and　finite　element　analysis，the　ultimate　load　calculation　and　the　ultimate　working　condition　analysis　of　jacket　are　performed.　Compared　with　NREL　5　MW　offshore　wind　turbine，the　mechanical　performance　of　a　series　of　optimized　topologies　with　various　leg　spacing　corresponding　to　the　adjustable　design　domain　are　superior　in　terms　of　fundamental　natural　frequency，maximum　displacement　and　maximum　pull-out　force.　By　altering　the　design　domain　of　leg　distance，the　optimization　results　illustrate　that　the　proposed　topology　optimization　approach　is　feasible　and　advantageous　in　jacket　design.　©　2024　Science　Press.　All　rights　reserved.