Offshore　wind　power　has　been　the　fastest-growing　form　of　renewable　energy　for　the　last　few　years,　owing　to　its　effectiveness　in　achieving　carbon　neutrality　through　a　reasonable　and　efficient　utilization　of　wind　power　resources.　With　offshore　wind　farms　gradually　developing　into　the　deep　and　far　sea,　greater　attention　is　paid　to　the　bearing　characteristics　of　foundations　for　offshore　wind　turbines.　Therefore,　it　becomes　significantly　important　to　explore　new　foundations,　effectively　promoting　the　development　of　offshore　wind　power.　Numerous　researchers　have　substantially　investigated　novel　foundations　for　offshore　wind　turbines　to　help　with　offshore　wind　farm　construction.　Compared　to　other　foundations,　the　pile–bucket　composite　foundation　has　obvious　advantages　in　terms　of　bearing　performance.　In　this　paper,　a　series　of　numerical　calculation　models　for　pile–bucket　composite　foundations　in　heterogeneous　saturated　clay　are　established　using　the　finite　element　software　ABAQUS.　Additionally,　the　undrained　shear　strength　changes　with　depth　are　examined　via　field　variables　to　explain　soil　heterogeneity　in　the　finite　element　model.　Next,　the　displacement　control　method　is　adopted　to　apply　the　vertical　loading　V,　horizontal　loading　H,　and　bending　moment　M　at　the　top　of　the　foundation.　Simultaneously,　the　ultimate　bearing　capacity　of　the　foundations　is　obtained　by　the　double　tangent　method,　and　the　bearing　capacity　factors　of　each　load　direction　are　obtained　by　normalizing　the　ultimate　bearing　capacity　in　different　calculations.　To　obtain　the　preliminary　design　method　for　the　size　of　pile–bucket　composite　foundation,　the　priority　of　influencing　factors　is　studied　through　the　orthogonal　test.　The　results　show　that　the　saturated　clay　coefficient　K　has　a　nominal　effect　on　the　vertical　bearing　capacity　coefficient　NcV.　When　K　is　different,　NcV　remains　almost　unchanged　for　a　certain　foundation.　Concerning　the　impact　of　bucket　shapes　on　the　bearing　capacity　coefficient　in　three　directions,　great　interaction　is　observed　between　the　diameter　D　and　the　buried　depth　L　of　the　bucket　structure.　The　diameter　of　the　bucket　has　the　greatest　influence　on　the　bearing　characteristics　of　the　pile–bucket　composite　foundations,　wherein　increasing　the　former　can　significantly　improve　the　latter.　The　research　results　provide　a　reference　for　the　design　of　the　pile–bucket　composite　foundation　of　an　offshore　wind　turbine.　©　2023　Science　Press.　All　rights　reserved.