NOVELTY - Preparation of wurtzite (Cu2ZnSnS4) nanocrystalline thin-film solar cell comprises mixing zinc sulfate solution with ammonia water, putting mixed solution in water bath at 50-100 degrees C, adding Cu2ZnSnS4 nanocrystalline dense film to solution, adding dropwise thiourea solution to solution, continuously deposition for 10-40 minutes, obtaining Cu2ZnSnS4 nanocrystalline dense film covered with zinc sulfide (ZnS) buffer layer, and sputtering zinc oxide layer, indium tin oxide conductive layer and nickel-aluminum (Ni-Al) electrode on dense film through magnetron sputtering.    USE - Method of preparation of wurtzite (Cu2ZnSnS4) nanocrystalline thin-film solar cell (claimed).    ADVANTAGE - The preparation does not need any vacuum equipment, is suitable for large-scale production, and utilizes environment-friendly material.    DETAILED DESCRIPTION - Preparation of wurtzite (Cu2ZnSnS4) nanocrystalline thin-film solar cell comprises ultrasonically cleaning substrate using ethanol and deionized water, coating substrate with molybdenum through magnetron sputtering, and obtaining flexible substrate; dispersing water-soluble Cu2ZnSnS4 nanocrystalline into water or ethanol to obtain dispersion, adding ammonia water or ethanolamine to dispersion at volume ratio of 1:5-10, obtaining aqueous Cu2ZnSnS4 ink, printing aqueous Cu2ZnSnS4 ink on flexible substrate, and performing light irradiation or sintering on the substrate to obtain a Cu2ZnSnS4 nanocrystalline dense film; and mixing zinc sulfate solution with ammonia water, putting mixed solution in water bath at 50-100 degrees C, adding Cu2ZnSnS4 nanocrystalline dense film to solution, adding dropwise thiourea solution to solution, continuously deposition for 10-40 minutes, obtaining Cu2ZnSnS4 nanocrystalline dense film covered with zinc sulfide (ZnS) buffer layer, sputtering zinc oxide layer, indium tin oxide conductive layer and nickel-aluminum (Ni-Al) electrode on dense film through magnetron sputtering, and obtaining Cu2ZnSnS4 nanocrystalline thin-film solar cell.