A　novel　composite　structural　member,　UHPC-encased　concrete-filled　steel　tubular　(UC-CFST)　column,　is　proposed　in　this　study　to　address　the　shortcomings　of　the　ordinary　concrete-encased　CFST　(OC-CFST)　columns.　A　total　of　22　specimens　subjected　to　axial　compression　loading　were　tested,　including　nine　UC-CFST　stub　columns,　nine　OC-CFST　stub　columns,　and　four　CFST　stub　columns.　The　experimental　results　showed　that　the　encasing　UHPC　of　UC-CFST　columns　was　less　damaged　than　the　encasing　ordinary　concrete　of　OC-CFST　columns　and　did　not　spall　when　the　UHPC　was　crushed.　The　UC-CFST　stub　columns　reached　their　ultimate　load-bearing　capacity　when　the　encasing　UHPC　attained　the　peak　compressive　strain,　which　was　much　greater　than　that　of　the　OC-CFST　stub　columns.　Compared　to　the　OC-CFST　stub　columns,　the　ultimate　load-bearing　capacity　of　UC-CFST　stub　columns　improved　markedly　by　75%-289%　and　the　compressive　stiffness　increased　by　22%-49%,　while　the　ductility　decreased　by　about　50%　on　average.　Furthermore,　increasing　the　area　ratio　of　the　encased　CFST　in　the　UC-CFST　stub　columns　was　unfavorable　for　the　compressive　stiffness　and　load-ultimate　bearing　capacity.　Finally,　by　comparing　the　different　calculation　methods　for　ultimate　load-bearing　capacity　of　OC-CFST　columns　recommended　by　Chinese　standard　CECS　188,　American　standard　AISC　360,　Japanese　standard　AIJ-SRC,　and　European　standard　Eurocode　4,　it　was　found　that　the　calculation　methods　applicable　to　OC-CFST　columns　would　underestimate　the　ultimate　load-bearing　capacity　of　UC-CFST　columns　to　varying　degrees.　Thus,　a　modified　calculation　formula　based　on　the　CECS　188　standard　was　proposed　for　accurate　prediction　of　the　ultimate　loadbearing　capacity　of　the　UC-CFST　stub　columns.