To　improve　the　structural　performance　of　the　connection　region　of　prefabricated　buildings,　a　new　assembled　precast　ultra-high　performance　concrete　(UHPC)　jacket　is　used　for　the　joint　of　precast　RC　column.　Experimental　and　theoretical　studies　were　carried　out　on　the　axial　compressive　behaviors　of　the　RC　composite　column　with　the　precast　UHPC　jacket　and　bolt　connectors.　The　effects　of　steel　fiber　content　and　thickness　of　precast　UHPC　jacket　on　the　axial　compressive　behaviors　were　analyzed　by　evaluating　the　peak　load,　elastic　stiffness,　ductility,　toughness　index,　and　energy　absorption　capacity.　A　partial　composite　column　with　the　interface　was　also　investigated　to　understand　the　effect　of　the　interface　between　the　composite　region　and　the　reinforced　concrete　region.　The　results　showed　that　diagonal　shear　failure　was　observed　for　all　specimens,　and　the　failure　of　partial　composite　column　occurred　in　the　RC　region　even　though　there　was　an　interface　between　the　composite　region　and　RC　region.　UHPC　jacket　could　significantly　improve　the　peak　load,　ductility,　and　energy　absorption　capacity　of　composite　column　but　had　little　effect　on　the　elastic　stiffness　and　toughness　index.　UHPC　jacket　with　steel　fiber　of　3　vol%　and　thickness　of　30　mm　performed　the　best　among　all　the　tested　specimens.　Under　sufficient　composite　confinement,　the　peak　load　improved　with　the　increment　of　confinement　index.　Further,　a　semi-empirical　model　considering　the　composite　confinement　of　the　UHPC　jacket　and　bolt　connectors　is　proposed　to　predict　the　peak　load　of　the　composite　column　and　validated　by　the　test　results.