Abstract: A platen superheater clamping tube of a station boiler had been leaked.The causes of tube burst were analyzed by means of macro examination, chemical composition examination, metallographic examination, impact test and microhardness test. The results show that, the reason of tube burst is that the TP347H tube is not treated with solid solution after cold bending, work hardening produces, the crack produced by chromium-poor intergranular leads to a decrease in strength, the materials can not meet the design requirements, and eventually brittle fracture occurs. For the avoidance of similar accidents, it is suggested that TP347H tube should be treated by solid solution treatment and stabilization treatment after cold working deformation.