Abstract: A physical and mathematical model for slabs heated in a 3-zone walking beam type of re-heating furnace was established. The finite difference method was used for discretization of the physical and mathematical model and a computational software was developed according to the software engineering theory. The results indicate that raising the temperature of reheating zone, the slab initial temperature and the emissivity of furnace gas can improve slab heating efficiency while guaranteeing the final quality of slabs. Reduction in heating zone temperature can decrease energy consumption and prolong the furnace campaign life.