A multi-level protection air leakage prevention device is specially used for the hot blast main pipe, which is specially suitable for the temperature measurement of the blast furnace the hot blast main pipe in the iron steel industry. The three-level protection measures of high-temperature seal strengthening tube, ferrule thread fastening core body external lead of high-pressure seal cover are used. When the front end of sensor is damaged due to some reasons, high-pressure hot air flow can be effectively controlled in the product to prevent the hot air blowing out harming the surrounding environment, to resist air flow erosion, corrosion wear, To realize the safe production of hot blast furnace vault a special design for the hot blast furnace vault temperature measurement in the iron steel industry. The unique counter blow device is adopted, the compressed air with pressure higher than the furnace pressure is used to hold the hot air in the protection room, so as to realize the cross temperature measurement type of safe production blast furnace: the high-temperature armored wire made of Inconel 600 material is adopted, with the maximum length of 10000mm the temperature resistance of 1200 ℃ C. The front end is equipped with ultra-high temperature alloy protection tube to extend the service life