The utility model discloses a flue gas desulfurization device with a coarse desulfurization function. The flue gas desulfurization device comprises an absorption tower and a gas inlet flue, wherein the gas inlet flue is connected with the gas inlet of the absorption tower, the gas inlet flue is provided with an accident spray system, and the accident spray system is provided with a spray pipeline I used for spraying limestone slurry. According to the flue gas desulfurization device, primary coarse desulfurization is carried out on flue gas inside the gas inlet flue by additionally arranging the spray pipeline I capable of spraying the limestone slurry in the accident spray system to reduce the desulfurization load of the absorption tower, so that the desulfurization efficiency of the desulfurization device is improved, and the standard discharge of the flue gas is realized; the limestone slurry inside the absorption tower can be directly used as the limestone slurry inside the spray pipeline I and participates in circular spray, an additionally arranged feed and discharge system can also be used, and the desulfurization device is unnecessary to greatly reformed, so that the equipment investment is reduced, and the manufacturing cost is reduced.