NOVELTY - Annular belt is formed using coated network, surface layer of silicone release agent is applied to belt, oven-dried, cured, master slurry and adhesive layer coating are applied, placed in oven and dried. Gas diffusion layer blank is peeled from the roll by peeling process and cooled in dry place. The master slurry is prepared by adding 30-100 g chopped carbon fiber or graphite fiber into dispersion obtained by dissolving dispersant in water and uniformly dispersing. The adhesive layer coating is prepared using 5-25% polyvinyl alcohol aqueous solution.    USE - Preparation of gas diffusion layer blank used for fuel cell.    DETAILED DESCRIPTION - Annular belt is formed using coated network via two splice of transmission belt. The belt is uniformly provided on driving guide roller, processed at rotating speed of 5-100 m/minute, the speed is controlled based on coating thickness, surface layer of silicone release agent is applied to the belt on driving guide roller arranged on fixed spray device using applicator in mesh conveyor belt, oven-dried, cured, spraying of silicone release agent is ensured, such that deposition and clog of transmission belt is prevented, master slurry is applied on surface of transmission belt, coating amount is controlled at 100-250 g/m2, then adhesive layer coating is applied on surface of obtained uniform coating film using fixed driving guide roller arranged on spraying device with spray volume of 20-100 g/m2, obtained product is placed in oven and dried. The above processes are repeated to achieve desired thickness of blank. Gas diffusion layer blank is peeled from the roll by peeling process and cooled in dry place. The master slurry is prepared by adding 30-100 g chopped carbon fiber or graphite fiber having length of 5-12 mu m and diameter of 5-12 mu m into dispersion obtained by dissolving 5-15 g dispersant in 5000 ml water, under stirring and uniformly dispersing using dispersing machine. The adhesive layer coating is prepared using 5-25% polyvinyl alcohol aqueous solution obtained by dissolving polyvinyl alcohol in deionized water. Thickness (H) of desired gas diffusion layer blank is calculated by relation: H=nKx QS%/V (I), where Q is amount of slurry applied to primary coating apparatus, S% is slurry solid content, V is operating speed of transmission belt, n is application time and K is empirical constant.