The temperature of the structural components without fire protection increases rapidly in fire, and it will result in significant? decline in the strength of steel and concrete. In order to investigate the mechanical performance of circular tubed steel reinforced concrete columns in high temperature, the effect of temperature on material properties and the asymmetry of temperature are analyzed, then the calculation method of bearing capacity of axial loading columns in fire is proposed. This method is verified by ABAQUS and good agreement is achieved. The parameters affecting the ultimate bearing capacity of columns in high temperature are studied using the method. The results show that the cross-section dimension and the strength of concrete and steel have significant effects on the ultimate bearing capacity, whilst the wall thickness of steel tube has little effect. The influences of load ratio, dimensions of specimen, and thickness of steel tube on the fire resistance are investigated by ABAQUS. It is shown that the cross-sections dimensions have significant effects on the resistance. However, with increase of load ratio and wall thickness of steel tube, the fire resistance is decreased.