The invention discloses a compound corrosion inhibitor for an internal cooling water hollow copper conductor of an electric generator and application of the compound corrosion inhibitor. The compound corrosion inhibitor comprises diphenol and/or polyphenol compounds, diamine and/or polyamine compounds and short-chain alkyl hydrosulfide. The prices of raw materials of the compound corrosion inhibitor are low; and the compound corrosion inhibitor is simple to prepare and convenient use, can meet the water quality control requirement of internal cooling water while guaranteeing a good corrosion inhibition effect, doesn't need a small mixed bed, a water quality control device and the like, remarkably reduces the investment, operation and maintenance costs of an electric generator set, and facilitates the popularization and application.