Abstract: After placement for a certain time in the room, the partial surface of 304H spring steel wire and spring rusted. The microscopic morphology of rusty part and unrusty part was observed, and the chemical composition was analyzed. The rusty cause of 304H spring steel wire and spring was discussed. The results show that the rusty part of 304H spring steel wire and spring had the normal microscopic morphology, but copper or zinc elements existed on the surface of the rusty part. The wire rod was polluted by copper element from baler shaft during finishing packaging, and was polluted by zinc element from drawing wheel surface during wire drawing. The potential difference was formed between copper or zinc elements and matrix solid solution, and electrochemical corrosion occurred on the surface of 304H spring steel wire and spring when a water film existed on the surface, resulting in the occurrence of partial rust.