Abstract: Taking the sealing ring bolts of a critical plant water pump as the research object, the causes of bolt fracture were analyzed through macroscopic inspection, chemical composition analysis, metallographic examination, hardness testing, and microscopic fracture analysis. The results showed that the primary cause of fracture was the poor water corrosion resistance of the bolt material, with obvious pitting corrosion observed on the fracture surface. Under the combined effects of electrochemical reactions and excessively high bolt hardness, the bolts eventually experienced fatigue fracture under alternating loads. It is recommended to replace the bolt material with duplex stainless steel to enhance water corrosion resistance and prevent electrochemical corrosion.