Furnace lining erosion is closely related to the operation stability and safety. The detection technology for hearth lining thickness of blast furnace was introduced.By using the data of thermocouples installed in the bottom of furnace hearth,a mathematical model of erosion was established; the real state of the hearth and bottom erosion was studied; the erosion condition was followed,serving for the furnace longevity. The detection technology for hearth lining thickness of blast furnace was introduced. By using the data of thermocouples installed in the bottom of furnace hearth, a mathematical model of erosion was established; the real state of the hearth and bottom erosion was studied; the erosion condition was followed, serving for the furnace longevity.