To investigate the fire performance of circular steel tube confined reinforced concrete (STCRC) columns exposed to natural fire, a finite element model including thermal analysis model and stress analysis model was developed using the software ABAQUS. The main considered parameters were fire heating rate, heating duration time and load ratio. Parametric temperature-time curves recommended by Eurocode 1 were employed as the temperature curves of natural fire, and the ISO-834 standard fire curve was selected as a comparison. The results showed that the faster heating rate and the shorter heating duration time of nature fire resulted in the higher temperature gradient of the composite cross section. Circular STCRC columns exposed to natural fire might fail in the heating phase or the cooling phase. Based on the method of equivalent fire exposure time, the fire resistance under natural fire and standard fire could be converted reciprocally and then compared with each other. It was found that fire safety design with ISO-834 standard fire curve was conservative when the heating rate of natural fire was slower than that of the standard fire. However, fire safety design with ISO-834 standard fire curve was unsafe when the heating rate of natural fire was faster than that of the standard one. Thus, natural fire curve in fire safety design is recommended for this condition.