Based on the analysis of the bearing mechanism of composite columns with core of high-strength concrete-filled steel tube,a new method to calculate the axial bearing capacity of the composite columns is proposed,which considers not only the difference in confinement effect between the concrete both inside and outside the tube,but also the influence of circular section and square section on the concrete outside the tube.The proposed method is then applied to the calculation of axial bearing capacity of 16 composite columns with core of high-strength concrete-filled steel tube,and the results are compared with those obtained by the existing methods.It is indicated that the calculated results accord well with the experimental ones,and that the proposed method is superior to the exis-ting methods because it can reasonably estimate the axial bearing capacity of composite columns with core of high-strength concrete-filled steel tube.