Abstract: In order to clarify the influence of chlorine element in blast furnace gas on auxiliary equipment, the source and occurrence form of chlorine element in blast furnace gas are discussed, and the harm caused by chloride ion to salt and scale accumulation of TRT blade, corrosion of gas pipe network and auxiliary equipment and corrosion of refractory material in hot blast furnace is summarized. In view of the harm caused by chloride ions in blast furnace gas, under the premise of not changing the process of blast furnace ironmaking, iron and steel enterprises have carried out a lot of attempts, mainly including the source control of raw materials from blast furnace, the development of pipeline anti-corrosion, blade anti-scale technology, after TRT spray alkali dechlorination, before TRT pipe spray dechlorination. Through the comparison of the advantages and disadvantages of the above four processes, it is suggested that the process of the combination of pipe injection dechlorination before TRT and anti-corrosion of key equipment may be the key research direction of blast furnace gas dechlorination in the future.