Abstract: A novel composite structural column, named a seawater sea-sand coral aggregate concrete (SSCAC) filled ultra-high-performance concrete (UHPC) tube (SFCT), was proposed and investigated in this study, which combines a prefabricated fiber reinforced polymer (FRP) hoop reinforced a thin-walled UHPC tube with the infill SSCAC. Total 13 groups of relative large-scale circular specimens were conducted under uniaxial compressive loadings, including 7 groups of SFCT specimens and 6 groups of control specimens. The main research parameters were selected as the volumetric hoop ratio, the type of FRP hoop, and the composite effect of the composite system proposed. The SFCT columns demonstrated the multi-crack failure mode on the UHPC tube without obvious peeling-off of UHPC covers, revealing that the UHPC tube effectively takes on the additional load released by the inner SSCAC during compacting. The test results showed that the load carrying capacity and the axial stiffness of SFCT columns have effectively increased compared with those of the corresponding control columns. The compressive performance of SFCT column increases with the increasing the volumetric hoop ratio in the UHPC tube. Additionally, using relatively flexible and low-cost basalt FRP (BFRP) and glass FRP (GFRP) hoops instead of carbon FRP (CFRP) hoops in the UHPC tube can further improve the compressive behavior of SFCT columns. Based on the experimental findings and on existing confinement models, a special model was proposed for predicting the axial load carrying capacity of SFCT columns. The analysis also indicated that the load carrying capacity contribution rate of the UHPC tube to the SFCT composite column is relatively stable within the parameter range of this study, with an average value of approximately 0.34.