The unidirectional breathable membrane is a material that can block resin and allow gas to pass through. This product is composed of two parts, a peel ply and a semi-permeable membrane, and is used in the“vacuum import resin ”process and the “wet vacuum bag molding process(prepreg or hand lay-up)”. The unidirectional air-premeable membrane can continuously extract air and volatiles to prevent the loss of resin in the laminate. In order to make the cured product easy to demold, the semi-permeable membrane surface of the unidirectional air-permeable membrane can be facing the glass fiber laminate, but note that this side cannot be used as a peel ply.