Coke dry quenching boiler tube and the corrosion products were systematically studied, and the failure cause of the boiler tube was proposed, which was the oxygen/sulphur corrosion and scour by hightemperature powder dust. For the tube with long service time, the oxygen and sulphur corrosion severely occurred in the wearresistant layer and slightly occurred in the interface layer, and only the oxygen corrosion occurred slightly in the metal base. However, the oxygen and sulphur corrosion severely occurred in the wearresistant layer, the interface layer and the crack in the tube with short service time. Besides, there were also some defects such as pearlite spheroidization and full decarburization layer in the internal surface in the tube with short service time. It was inferred that the boiler tube was overheated, which would aggravate the corrosion of oxygen and sulphur. Furthermore, the boiler tube suffered the scour by hightemperature powder dust, which was another significant cause of tube failure. Reducing the dust amount in the circulating gas, especially coarse particles, would effectively weaken the scour by dust and to control the temperature of the tube surface, which was the key to increase the service life of the tube.