Abstract: To research the oxidation status of billets in a reheating furnace when oxygen-enriched combustion was used, the influence rule of oxygen-enriched combustion atmospheres on the oxidation process of billets was studied by the self-designed experimental platform in the controlled atmosphere. The morphology of the oxide layer at different temperatures was analyzed. The results show that the oxidation process is divided into a fast oxidation stage and a slow oxidation stage. In the high temperature environment, CO₂ and H₂O have more effect on the oxidation of billets and the billets will be badly oxidized by high concentration of CO₂ and H₂O. The oxide layer is mainly composed of Fe₃O₄ and FeO.