Sulfur corrosion of steel is a universal problem in petroleum chemistry industry, paper and pulp industry, and alumina production industry. It has been proved by studies that the corrosion life of 3. 5 mm thick CT20 carbon steel was only 6 hours when it was in sodium hydroxide solution with 5 g / L S2-, and the corrosion rate of 16Mn steel was as high as 151. 21 mm / y when it was in sodium aluminate solution with 5 g / L S2-. The current research status of 4 forms of sulfur (S2-, S2 O2 3-, SO2 3-, SO2 4-) corrosion of steel in alkaline solution was reviewed in this paper, and the research progress of S2- corrosion of steel in alkali conditions was discussed particularly. Bayer process is the common method of alumina production with high-sulfur bauxite, during the progress, sulfur is transformed into sodium aluminate solution in the forms of S2-, S2 O2 3- and smaller amounts of SO2 3-, SO2 4-, leading to serious corrosion of the production equipment. At present, sulfur corrosion of steel in sodium aluminate solution is seldom reported, especially the coupled corrosive effects of different forms sulfur on equipment material when they coexist in sodium aluminate solution: the corrosion rate of 16Mn steel was dramatically reduced to 8. 66 mm / a from 151. 21 mm / a when 5 g / L S2 O2 3- was added into sodium aluminate solution with 5 g / L S2-. Finally, study on the mechanism of coupled corrosion was prospected.