Abstract: Corrosion perforation phenomenon happened to a boiler fire tube during service. Means of metallographic inspection, scanning electron microscope inspection, X-ray diffraction analysis, mechanical properties testing and chemical compositions analysis were used to analyze the corrosion perforation reasons of the fire tube. The results show that the corrosive perforation were mainly caused by oxygen corrosion of the boiler water, and high concentrations of chloride ion in the boiler water caused destruction of the passive layer of surface and speeding up the oxygen corrosion process. So corrosion perforation of the fire tube happened in a comparatively short time.