In fibrous porous media, some polymer materials are often used to control of surface property such as making hydrophobic surface and to make another function such as electrolyte. However, all of these polymers are not always distribute in porous media uniformly. The micro pores are blocked with it and it leads to the degradation of mass transfer and heat conduction. In this study, we focused coating and drying process of PTFE treatment to PEFC gas diffusion layer (GDL). By numerical analysis of evaporation and phase change of polymer in GDL, the effect of drying process on polymer distribution and porous property was examined. As a result, the PTFE distribution in the direction of through plane could be controlled by drying condition. These tendencies of experiment and calculation were almost equal to each other qualitatively.