A strain of killer yeast obtained from banana wine mash was treated by heat shock and ultraviolet ray (UV) (power: 20W, wavelength: 254 nm, irradiation distance: 50 cm), with varied exposure time. Five mutant phenotype colonies were obtained by the method of 2, 3, 5-Chloride Triphenyl Tetrazolium(TTC) screening. One mutagenic killer strain had highest yield of alcohol was selected through wort fermentation. And the final sugar was 1.71g/L, the final pH  3.8, soluble solids 2.86%, and the alcoholicity was 4.2%(V/V) after 7d fermentation of 10°BX wort at 20℃.