The invention provides a dedusting device and method capable of comprehensively recycling valuable metal in flue gas. The dedusting device comprises a molten pool, a reaction tower and an ascending flue. The molten pool is arranged on the lower portion of the reaction tower. The reaction tower is provided with a nozzle and a flue gas inlet. A space containing a coarse lead alloy layer, a molten iron layer and a slag layer is formed in the molten pool. The molten pool is provided with a lead discharging outlet, an iron discharging outlet and a slag discharging outlet which correspond to the coarse lead alloy layer, the molten iron layer and the slag layer respectively. A communication flue communicating the reaction tower with the ascending flue is further formed in the molten pool and located above the slag layer. The top end of the communication flue is provided with a plurality of spray guns. The molten pool wall corresponding to the slag layer is provided with side-blowing devices. Compared with a traditional dedusting device, the dedusting device capable of comprehensively recycling the valuable metal is better in dedusting effect, and meanwhile, the valuable metal in the flue gas is recycled by one step, so that the resource utilization rate is increased.