The effect of copper on the corrosion properties of mooring chain steel in synthetic seawater at room temperature were investigated by weight loss tests,electrochemical methods and corrosion product analysis.The results indicated that the mooring chain steel exhibited active dissolution behavior in synthetic seawater.Corrosion potential shifted to noble direction and corrosion current decreased with copper contents.Therefore,the weight loss reduced and the polarization resistance was increased with increasing copper addition.The improvement of corrosion with copper was attributed to the change of corrosion rust that became smaller granules with higher adhesion strength as well as thicker layer when the steel was added more copper content.Meanwhile,the microcrack of inner rust was prevented to grow.