The　determination　of　the　axial　bearing　capacity　of　large-diameter　steel　pipe　piles　is　a　crucial　aspect　of　the　design　of　pile　foundations.　However,　the　existing　methods　for　calculating　the　axial　bearing　capacity　of　pile　foundations　are　mostly　based　on　the　test　results　of　closed-ended　piles　or　small-diameter　steel　pipe　piles,　and　these　methods　are　not　applicable　to　large-diameter　steel　pipe　piles.　Based　on　the　existing　pile　foundation　bearing　capacity　calculation　methods　based　on　cone　penetration　tests,　a　modified　method　is　proposed.　By　comprehensively　considering　the　Poisson＇s　effect,　soil　plugging　effect,　and　side　resistance　degradation,　an　expression　for　the　pile　side　friction　resistance　is　derived.　Meanwhile,　the　base　resistance　is　divided　into　two　parts:　annular　resistance　and　inner　shaft　resistance,　and　the　proportional　relationship　between　cone-tip　resistance　and　these　two　resistances　is　established.　The　modified　method　is　used　to　calculate　the　axial　bearing　capacity　of　large-diameter　steel　pipe　piles　in　an　actual　offshore　engineering　project,　and　the　results　are　compared　with　those　obtained　using　six　commonly　used　existing　methods.　The　results　show　that　compared　with　the　existing　methods,　the　modified　method　is　more　accurate,　especially　in　terms　of　the　prediction　accuracy　of　pile　side　friction　resistance.　Additionally,　sensitivity　analyses　of　key　parameters,　including　pile　diameter,　pile　length,　plug　length　ratio,　and　cone　tip　resistance,　demonstrate　that　the　soil　plug　effect　significantly　influences　the　calculation　of　the　vertical　bearing　capacity　of　large-diameter　steel　pipe　piles　in　both　non-cohesive　and　cohesive　soils.　The　research　results　can　provide　theoretical　guidance　for　the　calculation　of　the　axial　bearing　capacity　of　large-diameter　steel　pipe　piles.　©　2025　Biodiversity　Research　Center　Academia　Sinica.　All　rights　reserved.