The invention provides a polyvinyl alcohol membrane. The polyvinyl alcohol membrane is produced through blow molding of melt-processible polyvinyl alcohol resin, the tensile strength of the polyvinyl alcohol membrane is not lower than 20 MPa, the melt-processible polyvinyl alcohol resin comprises effective amounts of polyvinyl alcohol, a plasticizer, soft water and a processing assistant, the degree of polymerization (DP) of the polyvinyl alcohol is 1000-3500, the degree of hydrolysis (DH) of the polyvinyl alcohol is greater than 72 (mol)% and is smaller than 99.9 (mol)%, the plasticizer is at least one of glycerol, polyethylene glycol and triethylene glycol di-2-ethylhexoate, and the processing assistant is at least one of talcum powder, silica, oleamide and saturated aliphatic dicarboxylate. The method has the advantages of simple process, less device investment, small occupied area, and realization of blow molding of normal-temperature, medium-temperature and high-temperature water soluble membranes. The method is mainly used for producing double-layer membranes, and the membranes can be directly processed to produce various water-soluble bags, and the water-soluble bags are used in the field of medium and low end packaging application, and can be used as a pesticide and chemical engineering product inner packaging liner bag, a hospital washing packaging bag and a refuse bag.