Aiming at the problem of iron oxide scale defect of low carbon steel in short process process, a systematic study was carried out from the macro and micro characteristics, and the causes of iron oxide scale defect were analyzed by combining with the key equipment of production line and the process characteristics of steel. The results show that the surface temperature of steel plate rises sharply in the process of tunnel furnace and induction heating process, and the oxidation rate increases rapidly, resulting in the increasing of scale stress. The content of C element in the steel is relatively high, the high-temperature gasification causes iron scale to blister, and the secondary iron scale is formed inside the blistering position, resulting in pressing in during the finishing rolling process and forming iron oxide scale defect. By adding 0.10%-0.15% Si element to the steel and optimizing the atmosphere in the tunnel furnace and the outlet temperature of induction heating at the same time, the occurrence of iron oxide scale defects is finally effectively reduced.