RPC-filled circular steel tube columns can be applied in long-span buildings, high-rise structures, and heavy loading constructions due to its excellent mechanical performance as vertical members. Currently, the formula of load-bearing capacity of RPC-filled circular steel tube column under axial compression is only applicable for the ones with a diameter less than 152 mm. When the diameter is larger than 152 mm, the calculated value is larger than test data. To solve this problem, finite element analysis on RPC-filled circular steel tube columns under axial compression was conducted using ABAQUS. The relationship of RPC confining stress ratio and RPC-filled circular steel tube column displacement curves were investigated. A total of 134 load-displacement curves of RPC-filled circular steel tube columns were calculated. Results show that when the confinement index is less than 0.5, there is no strengthening stage in load-displacement curves of the RPC-filled circular steel tube columns; when the confinement index is larger than 0.5, the strengthening stage in load-displacement curves occurrs; when the confinement index reaches 1, the ultimate load increases as much as 1.3 times that of the loading bearing capacity, and the ductility becomes higher. With same cross section of RPC-filled circular steel tube column, the lateral deformation coefficient and the confinement effect on core RPC increase with the decrease of RPC strength.Based on the results of experimental and numerical analysis, the calculation formula on bearing capacity of RPC-filled circular steel tube column under axial compression with diameter as large as 560 mm were proposed.