Abstract: Explosion of furnace tube for blast furnace high temperature super-heater of a petrochemical thermal power plant occured.The failure reasons were analyzed by means of fracture analysis,chemical composition analysis and microstructure observation.The results indicate that inside pearlite spheroidization and surface sulfurizing,occured in the furnace tube under the consecutive effect of furnace gas with high temperature,led to intergranular corrosion cracking and micro cracks formed which was the main reason for the tube explosion.