Surface decarburization is one of important issues in spring steel production. The novel decarbonization-resistant nano-coating has been successfully fabricated, by using a low-cost, and easily accessible bauxite minerals and other additional components, including magnesia, silicon carbide，glass powder and agglomerant, which is used to prevent spring steels from being decarburized during the hot-rolling process. The microstructure of the protective nano-coating is observed by means of X-ray diffraction, TG-DTA, metalloscope and so on. It is found that even if some glass ceramic exists within the coating in the initial lower temperature (950°C~1000°C) the decarbonization-preventing coating still presents decarburization resistance up to 72.2%. Furthermore, the protective ration reaches to 100% when the heating temperature rises to range (1050°C~1100°C). The excellent decarbonization preventing properties are attributed to the formation of glass ceramic and pleonaste, which hinders the second interdiffusion of oxygen and carbon.