Abstract: Six lactic acid bacteria strains isolated from the traditional sour soup were identified by 16S rDNA gene sequence analysis. Acid and bile salt tolerance of six isolates were studied. Antioxidant activity in vitro of six strains including 1,1-diphenyl-2-picrylhydrazyl(DPPH)radicals scavenging activity and hydroxyl radicals scavenging activity were measured. The results showed that six strains were Lactobacillus plantarum. The six strains exhibited desirable probiotic properties,showing over 10⁷ CFU/mL of viable count and over 87% of survival rate after incubation at pH2.5 and in the presence of bile salt at 0.3%. When adjusting the concentration of strains to 10⁸ CFU/mL,six strainss showed 23%~35% of DPPH radical scavenging rate and 6%~16% of hydroxyl radical scavenging rate. The strain L. plantarum JMST-1 showed a high level of survival rate in acid and bile tolerance tests(>91%)and desirable free radical scavenging activity(28.60% of DPPH free radicals and 15.44% of hydroxyl free radicals).