The invention discloses a flattening device for protection film winding, and relates to the technical field of film processing. The flattening device for protection film winding comprises a workbench, wherein a fan is installed on the upper surface of the workbench; an air outlet of the fan is connected with a main pipe; two vertically-arranged vertical plates are welded on the upper surface of the workbench; first support rods and a second support rod are installed between the two vertical plates; not less than three first support rods are provided; the not less than three first support rods are equidistantly distributed from the left to right; and a press roll is installed on each first support rod. According to the flattening device for protection film winding, which is disclosed by the invention, gas flow ejected by a spray head enables suspension parts at the two sides of a protection film to shake, thus preventing the edge of the protection film from adhesion and wrinkles; and moreover, the length of a support roll at the bottom of the protection film is gradually increased and the suspension parts at the two sides of the protection film are gradually reduced with the movement of the protection film from the left to right, thus a flattening purpose is achieved, the quality of the protection film is improved, and the winding is facilitated.