Abstract: The causes of rapid corrosion of 316L stainless steel shackle in seawater were analyzed by means of macroscopic observation, chemical composition analysis, hardness test, metallographic examination, scanning electron microscope and energy spectrum analysis and chemical digestion. The results show that the Cl^- in seawater and some ions released by the cable coating promoted localized corrosion on the surface of the stainless steel shackle. Some regions of the cable and the shackle formed a gap structure, and the gap corrosion occurred in these area under the action of long-term fretting wear and microbial catalysis.