In recent years， antioxidant peptides with high safety， potent antioxidant capacity， become a hot research field. This research is mainly engaged in oxidative stress inhibitory activity of egg white peptides. This study takes the pepsin hydrolysates from egg white ovomucin as raw materials， and pentapeptides from egg white as research object. The antioxidant activity of pentapeptides from egg white protein were evaluated using different chemical methods with different mechanisms. The pentapeptide CFDVF showed extraordinary DPPH scavenging activity （50.14% ± 2.1% at the concentration of 1.0 mmol/L）， VYQFL exhibited the strongest ABTS free radical scavenging ability [TEAC value = （94.66 ± 0.37） μmol/L TE/100 μmol/L]， WNWAD showed extraordinary oxygen radical absorption capacity [ORAC value = （2.53 ± 0.18） μmol/L TE/μmol/L]. Secondly， in order to further examine the antioxidant activity of pentapeptides from egg white， the oxidative stress model of HEK293 cells was established by MTS assay. WNWAD （Trp-Asn-Trp-Ala-Asp） exhibited the strongest oxidative stress inhibitory activity. The pentapeptides showed no stimulatory or cytotoxic effects in HEK293 cells. Finally， the WNWAD was screened out to carry out the research on mechanism of pentapeptides from egg white against oxidative stress in human embryonic kidney 293 cells. The MDA production and cellular activity of LDH， CAT， T-SOD， and GSH-PX were measured by kits. The results showed that WNWAD inhibited cell oxidative stress by increasing intracellular LDH activity and reducing intracellular MDA content. Enzyme activity results displayed that WNWAD dose-dependently increased the activity of SOD1， CAT and GPx1 in HEK293 cells. The effect of WNWAD on the protein expression of SOD1， CAT and GPx1 in HEK293 cells was analyzed with western blotting. Compared to the control， a concentration-dependent up regulation of SOD1， CAT and GPx1 protein expression by the WNWAD could be seen.