The aconitic acid-acrylic acid copolymer was synthesized by using citric acid as the main material,and that was compounded with polyaspartic acid and zinc salt to get a new kind of high-efficient corrosion inhibitor terpolymer,which performances of corrosion inhibition,scale inhibition and biodegradability were evaluated.The results showed that the terpolymer was suitable to treating the hard water,when the dosage of the agent was 14 mg/L,the corrosion inhibition rate to A3 carbon steel could reach over 96%.The biodegradable rate was 87 % after 28 days,so the agent was a kind of biodegradable corrosion inhibitor.