Abstract: The fracture of a marine diesel engine stud was analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, mechanical property test and fracture analysis. The results show that due to the contact of the rod body with the corrosive medium, pitting corrosion occured. Therefore, under the action of tensile stress, stress corrosion cracking was caused by pitting corrosion pits, which eventually led to the fracture of the stud.