Abstract: The fracture cause for waterwall suspending tube in a power station boiler was analyzed by macroscopic examination, chemical composition analysis, metallographic analysis, tensile test, impact test, hardness test, fracture analysis and comprehensive analysis. The results show that the fracture mode for waterwall suspending tube was transgranular and fatigue fracture, the main reason is high frequency vibration in the operation of the suspending tube, the work hardening of the suspending tube elbow and weld defects of steel plate play a promoting role on the formation of cracks. Finally, the preventive measures are put forward for fracture cause.