A machine for flat mounting of flexographic printing plates, comprising a base, a table, supported by said base, defining a support surface for mounting a printing plate on a respective support. The table comprises a front side, a rear side and two opposing sides. The machine also comprises parallel lateral guides, provided along the sides of the table, a carriage slidingly engaged in the lateral guides, a pressure roller associated with the carriage, to determine the adhesion of the printing plate on the respective support, and a vacuum generation system, to constrain the support to the surface of the table, during mounting of the printing plate. The machine comprises at least one layer of fabric, or breathable material, positioned on the surface of the table, on the upper surface of which the support is intended to be positioned, for the subsequent mounting, on it, of the printing plate.