To　enhance　the　axial　compressive　bearing　capacity　and　durability　of　concrete-encased　concrete-filled　steel　tubular　columns　(referred　to　as　OC-CFST　columns),　a　novel　approach　utilizing　ultra-high　performance　concrete　(UHPC)　encased　CFST　(UC-CFST　columns　for　short)　was　proposed.　A　total　of　22　stub　column　specimens　were　tested　under　axial　compression,　including　nine　UC-CFST　columns,　nine　OC-CFST　columns,　and　four　CFST　columns.　The　investigation　aimed　to　assess　the　impact　of　encasing　material　strength　and　area　ratio　on　the　axial　compressive　performance　and　failure　mode.　Finite　element　models　of　the　UC-CFST　stub　column　were　established　using　ABAQUS,　and　a　parameter　analysis　of　axial　compression　performance　was　conducted　on　the　stub　columns　with　real　structural　dimensions.　The　results　reveal　that　during　failure　of　OC-CFST　stub　columns,　the　encasing　ordinary　concrete　suffers　extensive　peeling,　while　UC-CFST　stub　columns　experience　relatively　intact　due　to　the　bridging　effect　of　steel　fibers　within　the　UHPC.　Compared　to　the　OC-CFST　stub　columns,　the　UC-CFST　stub　columns　exhibit　significantly　improving　axial　compressive　stiffness　and　axial　compressive　bearing　capacity,　and　reach　axial　compressive　bearing　capacity　when　the　UHPC　encasing　reaches　its　peak　compressive　strain.　Furthermore,　while　maintaining　the　outer　diameter　of　composite　columns　constant,　the　axial　compressive　bearing　capacity　of　UC-CFST　stub　columns　demonstrate　an　approximately　linear　increase　with　the　rise　in　area　ratio　of　encasing　concrete,　while　the　OC-CFST　stub　columns　exhibit　a　linear　decreasing　trend.　Finally,　the　applicability　of　using　the　formula　in　the　current　technical　specifications　for　steel　tube-reinforced　concrete　column　structures　to　calculate　the　axial　compressive　bearing　capacity　of　UC-CFST　stub　columns　was　analyzed.　Based　on　this　formula,　it　was　recommended　not　to　consider　the　additional　coefficient　of　0.　9　and　a　new　calculation　method　was　proposed　to　accurately　determine　the　axial　compressive　bearing　capacity　of　UC-CFST　stub　columns.　©　2023　Science　Press.　All　rights　reserved.