Abstract: Since the temperature distribution and erosion of blast furnace hearth are directly affected by cooling system,a rational cooling water system is the assurance for long campaign life of large blast furnace.Combined with a 4 000m³ blast furnace,physical and mathematical models of temperature fields of blast furnace hearth and bottom were built according to heat transfer theory.Two different hearth cooling systems,namely "low water capacity and large temperature difference" and "large water capacity and small temperature difference",are both investigated by modeling and numerical simulation.Effects of different cooling systems on hearth temperature field,hearth erosion and blast furnace life are also analyzed.The results indicate that during the initial period with thicker brick lining,effects of different cooling systems on blast furnace temperature distribution are nearly the same.As the brick lining gradually becomes thinner,different cooling systems have much different effects on temperature distribution.When the brick lining is eroded to a certain level,even the best cooling system is of no use,but "large water capacity and small temperature difference" and enhanced cooling measures will slow down the erosion and prolong the campaign life.