The utility model relates to a hydraulic stirring device of a flue-gas pre-washing tower. The hydraulic stirring device comprises a tower body of the pre-washing tower, wherein the outer side of the tower body is provided with a hydraulic stirring pump which is connected with a hydraulic stirring pipeline; the hydraulic stirring pipeline extends into the tower body of the pre-washing tower and is provided with a plurality of spraying nozzles. The hydraulic stirring device has the advantages that the hydraulic stirring pipeline and the spraying nozzles are uniformly distributed in the tower body of the pre-washing tower, and all the areas covered by slurry are stirred, so that solid particles are suspended in the slurry all the time; by a hydraulic stirring mode, all the slurry in the tower is effectively stirred, so that the applicability to round and square pre-washing tower is achieved, the problems of difficulty in material selection and larger initial investment of the stirrer are effectively solved, and wide application in the field of flue-gas pre-washing can be achieved.