Atmosphere-protected roller bottom continuous normalizing and tempering production line is suitable for normalizing and high-temperature tempering heat treatment of special steel (including asymmetric spherical flat steel and symmetric spherical flat steel), ordinary low-temperature section steel and 5Ni low-temperature section steel. It consists of loading and unloading conveying line, normalizing and tempering heat treatment furnace and air-cooling room. Heat treatment furnace adopts nitrogen protective atmosphere, its own preheating burner radiation tube indirect heating, pulse control. The material is heated and cooled evenly during the heat treatment process, and the surface of the material is smooth, oxidation-free and slightly decarburized after the heat treatment. Depending on different needs, single gear motor can be used to drive the whole line or single roller independent drive mode. Driving system frequency conversion speed regulation, direction can be controlled, and can be equipped with material tracking system, air-cooled room air volume can be controlled to ensure the cooling speed and straightness of the profile.