NOVELTY - Preparing polyvinyl acetate-polyethylene oxide-microcrystalline cellulose -water alkaline polymer electrolyte comprises dropwise adding microcrystalline cellulose (MCC) solution into polyvinyl acetate (PVA) solution, heating to obtain PVA/MCC solution, cooling, adding the alkali solution into PVA/MCC solution, stirring, adding polyethylene oxide (PEO) solution into the PVA/MCC/alkaline solution, adding glycerin, and stirring until a uniform solution is obtained, then vacuum degassing and casting, drying to obtain basic polymer electrolyte membrane.    USE - The electrolyte is useful for alkaline fuel cell (claimed).    DETAILED DESCRIPTION - Preparing polyvinyl acetate-polyethylene oxide-microcrystalline cellulose -water alkaline polymer electrolyte comprises (i) dissolving polyvinyl acetate (PVA) in deionized water and heating with stirring at 98 degrees C to obtain a stable solution; dissolving polyethylene oxide (PEO) in deionized water and heating with stirring at 70 degrees C, to obtain a stable solution; dissolving alkali in deionized water to obtain a stable solution; dissolving lithium chloride in dimethylacetamide, to obtain a stable solution, where the mass ratio of lithium chloride and dimethylacetamide is 7:93, and adding microcrystalline cellulose into lithium chloride/dimethylacetamide solution, heating with stirring at 85 degrees C for 5 hours, and uniformly dispersing microcrystalline cellulose to obtain microcrystalline cellulose solution; (ii) dropwise adding microcrystalline cellulose (MCC) solution into PVA solution at 98 degrees C, continuing heating with stirring, to obtain PVA/MCC solution, cooling to room temperature and stirring, dropwise adding the alkali solution into PVA/MCC solution, stirring, dropwise slowly adding PEO solution into the PVA/MCC/alkaline solution, adding glycerin, and stirring continuously until a uniform solution is obtained; then vacuum degassing and casting in a polytetrafluoroethylene mold, drying at 30 degrees C for 12 hours to obtain the basic polymer electrolyte membrane; where the mass ratio of microcrystalline cellulose to PVA/PEO is 1:99-10:90; and the mass ratio of PVA, PEO and alkali is 40:10:50-36:9:55.