The utility model provides a boiler flue gas desulphurization device, which comprises a concentrating tower and an absorption tower. A flue gas pipeline is arranged between the concentrating tower and the absorption tower, the upper portion of the concentrating tower is provided with a first mixed liquid inlet, the middle of the concentrating tower is provided with a flue gas inlet, the top of the absorption tower is provided with a flue gas outlet, the upper portion of the absorption tower is provided with a second fixed liquid inlet, the lower portion of the absorption tower is connected with a first restarting injector via a pipeline, the other end of the first restarting injector is connected with a first liquid pipeline, the first liquid pipeline is connected with one end of a second liquid pipeline, the other end of the second liquid pipeline is connected with one end of a second restarting injector, a third liquid pipeline is connected with one end of a fourth liquid pipeline, and the other end of the fourth liquid pipeline is connected to the bottom of the absorption tower. By aid of the boiler flue gas desulphurization device, mixed liquid can be recycled sufficiently, power during the flue gas desulphurization device is reduced greatly, and desulphurization cost is then reduced. Besides, oxidation degree of ammonium sulfate is regulated by directly regulating intake valves of the restarting injectors, thereby increasing production safety coefficient and the like.