Abstract: In this paper the effect of furnace dust on the HCl removal in the top gas of blast furnace had been investigated.When ash content in gas baghouse increases within the level less than 5 mg/m³,the HCl removal can be improved.When the particle size of dust is less than 38 μm,increasing size can slightly improve the dechlorination effect,however,excess size will lead to rapid removal effect decreasing. The suit-able location for installing HCl removal equipment shall be the downstream of cloth bag dust remover, and the baghouse ash through purification can be used as an active additive into blast furnace top gas dechlorination agent.The gravity dust will deteriorate the effect of removing chlorine in the blast furnace top gas.