Formation behavior and performances of anodic film grown on AZ31B alloys were systematically studied in Na2SiO3 system electrolyte with varying triethanolamine (TEA) content. The growth behavior and appearance of anodic film were significantly affected by the TEA content. The film growth speed increased because of the addition of TEA. Whitish gray lubricous barrier-type film were obtained in the electrolyte with TEA. The film density was obviously increased by the addition of TEA. Moreover, the film produced in electrolyte with TEA possessed a high degree of corrosion resistance and obviously better than that formed in electrolyte without TEA. EDX analysis indicates that, as the concentration of TEA increased, the contribution of the elements from the base alloy increased.