Abstract: The antioxidant activities of fermentation supernatant,intact cell suspension and intracellular extract of 5 strains of lactic acid bacteria before and after inactivation were compared by total antioxidant activity(T-AOC),total superoxide dismutase(T-SOD)activity,hydroxyl radical scavenging rate(OH^-·),superoxide anion scavenging rate(O₂^-·)and reducing activity. 3 strains of lactic acid bacteria with relatively strong antioxidant capacity were screened for compounding. The results showed that the fermentation supernatants,intact cell suspensions and intracellular extracts of the five lactic acid bacteria before and after inactivation had different antioxidant capacity. The fermentation supernatants before and after inactivation of Lactobacillus acidophilus had highest total antioxidant activity,45.9 U/mL and 35.0 U/mL,respectively. The scavenging ability of superoxide anion free radical in the non-inactivated fermentation supernatant of Sporolactobacillus inulinus was strong,which was 21.03%. The inactivated intracellular extract of Streptococcus thermophilus had the strongest total superoxide dismutase activity of 456.7 U/mL,and its non-inactivated intracellular extract had the higest hydroxyl radical scavenging rate of 79.26%. The inactivated fermentation supernatant of Lactobacillus salivarius had the strongest reducing activity. The combination of Lactobacillus hesporum,Lactobacillus salivarius and Lactobacillus acidophilus showed that the superoxide anion scavenging rate(O₂^-·)of inactivated intact cell suspension was higher than that of the single strain;The hydroxyl radical scavenging rate(OH^-·)of the inactivated intact cell suspension after the combination of Bacillus and Lactobacillus acidophilus was the strongest,which was 82.40%;The total antioxidant activity(T-AOC)and total superoxide dismutase(T-SOD)activity of the mixed strains were not significantly different from those of the single bacteria. Different fractions from lactic acid bacteria have different antioxidant activities in vitro. Therefore,lactic acid bacteria from difference resources,concentrations and excretion places also exhibited different antioxidant activities.