It is an important link of resource utilization to remove high mass fraction chlorine salt from blast furnace bag dust. The blast furnace bag dust of an iron and steel enterprise is taken as the research object, its chemical composition is analyzed, and the micro-morphology and crystal composition of the bag dust before and after wet leaching are characterized. The wet removal mechanism is explored, and the effects of process parameters such as liquid-solid ratio, leaching time, stirring rate and leaching temperature on dechlorination rate are further studied. The results show that the chlorine in blast furnace bag dust mainly exists in the form of zinc chloride, sodium chloride and potassium chloride. The migration process of wet leaching dechlorination is mainly the process of dissolving soluble chloride slats and removing it, in which the ratio of liquid to solid has the greatest influence on the dechlorination. Under the optimum conditions of liquid-solid ratio of 2, leaching temperature is 50 ℃, leaching time is 10 min and stirring rate is 200 r/min, the rate of dechlorination in bag dust can reach over 90%. Dechlorination is mainly affected by diffusion conditions, and the apparent activation energy of the initial reaction is 3.24 kJ/mol.