The function of the rolling furnace is to heat the billet. Generally called continuous heating furnace and walking heating furnace. The preheating, heating and isothermal of the billet are completed at one time. Driven by the pusher, the billet enters the preheating zone in the furnace for preheating, and gradually enters the heating zone. The moving speed is determined according to the cross-sectional area of the billet. Isothermal is to ensure that the temperature difference between the inside and outside of the billet is small and the temperature is uniform. It makes the billet deform and rationally eliminate some internal defects during rolling.