Abstract: Objective:The aim of the present study is to investigate the effect of Pediococcus pentosaceus P36 on antioxidant function of HepG2 cells under oxidative stress. Method:HepG2 cells were randomly divided into 3 groups:Control,model(H₂O₂ induced oxidative stress)and treatment(H₂O₂ plus Pediococcus pentosaceus P36)groups. Antioxidant activity in culture supernatants and lysates of HepG2 cells at 12 h and 24 h were measured. 4',6-Diamidino-2-phenylindole(DAPI)staining was applied to observe cell morphology in different groups by fluorescence microscopy. Results:Total antioxidant capacity(T-AOC),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and catalase(CAT)activities in the culture supernatant,as well as SOD activity in the cell lysate at 12 h in the treatment group were significantly increased when compared with their counterparts in the model group(p<0.05). At 24 h,the activities of antioxidant enzymes(p<0.05)were significantly increased(p<0.05),and the content of glutathione(GSH)and malondialdehyde(MDA)in the culture supernatant in the treatment group were significantly decreased(p<0.05).A significant decrease of 19.76% in SOD activity in the cell lysate was observed for the treatment group compared with the model group(p<0.05). Moreover,at 24 h,the level of damaged cells was reduced in the treatment group than that in the model group,and most cells in the former group had normal morphology. Conclusion:The addition of Pediococcus pentosaceus P36 could increase antioxidant function of HepG2 cells under oxidative stress.