The experimental study was carried out on 12 carbon fiber reinforced composite(CFRP) confined reactive powder concrete(RPC) filled steel tube(CRST) short columns. The core of the short columns was RPC with a strength of 100160MPa, and the external constraints were steel tubes with a wall thickness of 2 or 4mm and two layers of CFRP. The results show that compared with ordinary concrete, RPC material has higher compressive strength, more obvious brittleness in the state of no external constraints, and larger corresponding strain when the ultimate bearing capacity is achieved. Failure modes of CRST short columns under axial compression occur shear failure and end compression drum failure. The load displacement curves of CRST short columns are mainly divided into linear elastic stage, elastoplastic stage, failure stage and platform stage. Considering the double constraint of CFRP and steel pipe on core RPC, the influence coefficient IF is proposed to represent the improvement degree of CFRP and steel pipe on ultimate bearing capacity, and the expression of IF is obtained by linear regression fitting. At the same time, it is assumed that the steel pipe has yielded when reaching the ultimate bearing capacity of CRST short columns. The ultimate bearing capacity of CRST short columns is calculated by the method of limit equilibrium analysis. A fitting formula is obtained which is in good agreement with the test results.