The heat transfer performance of concrete-filled steel tube buckling-restrained-brace was analyzed by ABAQUS. The results showed that the temperature distribution of core plate was uniform. And the temperature of core plate was only 25 percents of that of the outer tube. The changes in load-bearing capacities of BRB under different fire durations were calculated according to Technical Code for Antifire of Building Steel Structure ( CECS 200 ∶ 2006) . Under the results of FEM analysis,the recommend spraying range of fire retardant coatings of BRB was presented.