4,4'-Diaminodiphenyleulfidetetraacetic acid can be obtained by heating 4,4'-diaminodiphenylsulfide with chloroacetic acid in water solution at 95-99℃ for 4 hours,keeping the pH at 7-8 all the time with addition of alkali,followed by cooling the reaction mixture to 00C and neutralizing with hydrochloric acid.The yield is 79.5% based on 4,4'-diaminodiphenylsulfide.