Method and device for lowering stripes of photomask plate

The invention is applicable to the field of photomask production, and particularly relates to a method and device for lowering stripes of a photomask plate. The method comprises the following steps: calculating the pattern contraction coefficient of stripes due to light beam energy variance according to the light spot size of photoetching equipment and the quantity of light beams; contracting all vertexes in the pattern according to the contraction coefficient to obtain a contracted pattern; and before photoetching, carrying out back repair on the contracted pattern on the equipment by using the opposite coefficient according to the contracted pattern. The pattern of the photomask plate adopted by photoetching is subjected to back repair according to the reasons for generating photomask plate stripes, so that the back repair effect after photoetching counteracts the stripes caused by errors, thereby lowering the stripes of the photomask plate.