The utility model discloses an efficient denitration improvement device for a circulating fluidized bed boiler. The denitration improvement device comprises a hearth, a flue, a support steel frame, a primary duct and a secondary duct, wherein the primer duct is arranged on the flue, the secondary duct is connected with the hearth and the flue, the hearth comprises a water cooling wall pipe, a front wall, a water tank and a boiler barrel, four steam and water separators are additionally arranged in the boiler barrel, a supercooling screen is additionally arranged on the outer wall of the front wall, three overheating screens are added on the front wall in nearby positions near the supercooling screens, a set of secondary water spraying temperature reducer and connecting pipeline is additionally arranged between a position near the top of the flue and the supercooling screens, a layer of secondary duct is added on the denitration improvement device, and the lowest layer of the secondary duct is provided with the primary duct in an improved way. The efficient denitration improvement device has the advantages that the effect of reducing the denitration quantity of the circulating fluidized bed boiler to be lower than 250Ng/Nm3 can be realized, in addition, the structure is simple, the cost is low, and the realization is easy.