Abstract: By means of visual observation,chemical compositions analysis,metallographic examination andmechanical properties testing,the bursting causes for T92steel tube of finishing superheater in ultra supercriticalboiler were analyzed.The results show that the tube-bursting was due to long term overheat,as a result of a littleoxide skin peeling-off from the local position of inner wall of the tube.Preventive measures were proposed in view ofthe bursting reasons.