In this experiment,17 lactic acid bacteria(LAB) were separated from traditionally home-made kumiss and industrial production kumiss,and the acidity ability of other 15 strains were determined,and the mix fermentation was carried out using the strains 511 and K2 with the yeast.The results showed that acid production level of 15 lactic acid bacteria were different from each other.The Lactic acid bacteria with shrong acid production ability were cultured for 24 hours,under the pH=4.0.The Lactic acid bacteria with low acid production ability were cultured for 24 hours,above the pH=5.0.In combination ferment experiment of lactic acid bacteria and yeast,acidity combination was 2combination 1combination 3.