A corrosion survey was made for the subway rails at Wuhan city of Central China, focusing especially on the corrosion related environments in tunnels of subway stations in service or under construction. The chemical composition of the collected water samples, the microstructure and phase constituents of corrosion products on subway rails were examined. The results show that according to the difference in the corrosion degree of subway rails and the quality of relevant waters collected from various tunnels, the corrosion environments encountered for the subway rails can be divided into four categories: humid atmosphere, sewage immersion, cement mortar as cover, and stray current. As the subway rails in service or storage in the above four types of environments, the corrosion degree of the rails is different: in the humid atmosphere, the formed corrosion products on rails (in service) are compact and stable with protectiveness to certain extent; in the condition of sewage soaking and cement mortar as cover, the rails (under construction) experienced local bubbled corrosion and uniform corrosion with the participation of Cl^-; while the stray current induced corrosion (in use) can directly cause the damage of the rail bottom, which is the fastest and the most severe corrosion of the subway rails, what we've seen up to now. In view of the corrosion of rails in different environments, the corresponding protection measures are also put forward.