Abstract: The cracks of 304 austenitic stainless steel washer were studied by means of chemical composition,tensile test and scanning electron spectroscope(SEM). The result showed that the cracks originated from bolt slot and stress corrosion cracks (SCC) were the main reasons of the crack. Chloride containing in the coastal atmosphere and overstress/over-deformation of the washer at the bolt slot caused by improper assembling were responsible for the SCC.