Double louver damper for flue gas desulfurization are developed by fully absorbing foreign advanced technology. They are used in inlet, outlet or bypass flue ducts of absorption tower of flue gas desulfurization system, or in flue gas denitration and flue gas dust removal system. Double louver damper usually adopt louvered double-deck baffle structure. When shutting off, high-pressure sealed air is introduced between double-deck dampers to isolate and shut off flue gas.