Based on the problems of high acidity and high residual sugar content in the process of strong-flavor liquor production, the yeast in medium and high temperature Daqu was preliminarily identified by plate streaking purification, WL medium morphology observation and microscope observation. Then, the yeasts with strong acid resistance and alcohol production ability were screened by TTC medium staining and differential acidity medium, and the molecular biology identification, biological characteristics and fermentation test of fermented grains were carried out. The results showed that the strain dq1 screened in medium and high temperature Daqu had strong growth activity at pH 3.0, and the alcohol concentration was 0.87%vol. It was identified as Saccharomyces cerevisiae and had the characteristics of tolerance to pH 3.0, high temperature （48 ℃） and alcohol concentration of 6%vol. The utilization rate of reducing sugar in the fermented grains was increased by 14.9% in the fermentation test. The alcohol content in the fermented grains was effectively improved, and the yield of fermented grains was increased. It provided dominant yeast for the fermentation of Luzhou-flavor liquor.