In this study, we screened 9 potent probiotic strains with good acid and bile tolerance in vitro from the dominant lactic acid bacteria of traditional fermented milk in Sayram, Baicheng County, Xinjiang, which is known as a town of longevity in China. All 9 probiotic strains of lactic acid bacteria exhibited very strong tolerance to pH 2.0. The viable cell counts of strains S5-8 and S2-1L were more than 108 CFU/mL after exposure to simulated gastric fluid, with S5-8 growing vigorously. The viable cell counts of 7 other strains exceeded 107 CFU/mL, which were much higher than the critical value of 106 CFU/mL.