Abstract: In this paper, the fractographs of pressurized aluminum cylindrical tanks damaged by the inner pressure and laser irradiation have been analyzed. It is found that the mechanism of crack formation and development in the area irradiated by the laser beam is ductile because there are many ductile dimples in the fractographs. Some fractographs show that there are two layers on the shell wall due to the stress distribution, the outer one was induced by the plastic deformation, and the inner one consists of many ductile dimples. The relations between the stress distribution and cracks, also the development process of crack, are discussed in this paper, which is conducible to better theoretical study on this problem