Abstract: Corrosion inhibition synergism of metallic cations Cu2+ and non ionic surfactant OP for steel in hydrochloric acid medium was investigated by weight loss method.It is found that the corrosion inhibition of either Cu2+ or OP is rather low,but when they are mixed,the corrosion inhibition for steel increases greatly at a wider concentration range,and a strong corrosion inhibition synergismis shown.This result has an important theoretical meaning for the study of the advanced mixed inhibitor of steel.