The invention discloses a flue gas water film deduster with a function of automatic dedusting. The flue gas water film deduster comprises a casing, a flue gas inlet pipe, a flue gas outlet pipe, a plurality of diversion pipes and a water pool. The flue gas inlet pipe and upper and lower pipes of the diversion pipes are hinged. The lower pipes are inclined. Two sides of each one of the flue gas inlet pipe and the lower pipes of the diversion pipes are hinged to connection rods. Two ends of the connection rod are hinged to levers. Two sides of each grade of a dedusting chamber casing are provided with fixed supports. The bottom of the water pool is provided with the several supports. The supports are provided with sliding rails. Two sides of the sliding rail are slidingly connected to several pairs of opposite sliding blocks. The opposite sliding blocks are fixedly connected by a connection rod. A rotator is rotatingly connected to the connection rod. The rotator is provided with blades. Under the action of the sliding rails, the blades rotate and move to produce a water film for dedusting.