Abstract: FRP confined concrete encased cross-shaped steel (FCCCS) composite column can solve the problems arising from the weaker lateral performance of FRP confined concrete because of the lack of longitudinal reinforcement. The embedded cross-shaped steel with flanges not only enhances the axial load bearing capacity of the composite column but also provides additional confinement to the core concrete and eventually to improve the performance of the composite column. In order to develop a method for calculating the axial compressive capacity of FCCCS composite columns applicable to various concrete strengths, this study conducted an axial compression experiment on four FCCCS composite columns and analyzed their axial characteristics. The test results showed that FCCCS composite columns with UHPC cores exhibit an excellent axial compressive performance. With an increase in the FRP layers from 14 to 16, the load-bearing capacity of the specimens increasing exceed 13%. Additionally, increasing the length of the steel flanges from 18 mm to 36 mm will result in a 1.4% increase in load-bearing capacity. Based on the failure mechanism and confinement analysis, the core concrete was divided as two zones, FRP confined zone and, the combination of FRP and steel confined zone, according to the resource of confinements. For the FRP confined zone, the FRP confinement coefficient was proposed. For the FRP and steel combined confined zone, considering the non-uniform confinement from the steel sections, an effective confinement coefficient for cross-shaped steel with flanges was introduced. The load bearing capacity model of FCCCS composite column was proposed by superimposing the load-bearing capacities respectively from the FRP confined zones, the FRP and steel combined confined zones and, the steel, respectively. The influence of the critical parameters of FCCCS on the load-bearing capacity was further analyzed.