Objective To investigate whether overweight and obesity might cause oxidative stress and potential oxidative damage in overweight and obese children, and to explore its possible mechanism. Methods Eighty-five overweight and obese children (OOC), and eighty-five age-matched healthy children (HC) were recruited in this case-control study. The present study analyzed spectrophotometrically vitamin C (VC), vitamin E (VE), and β-carotene (β-CAR) in plasma, as well as the activities of superoxide dismutase (SOD), catalase (CAT), and the level of malondialdehyde (MDA) in erythrocytes. Results Compared with those of VC, VE, β-CAR, SOD, CAT and MDA in the HC group, the average values of VC, VE, β-CAR, SOD, and CAT in the OOC group were significantly decreased (P<0.001), while the average value of MDA in the OOC group was significantly increased (P<0.001). The regression analysis demonstrated that VC, VE, β-CAR, SOD, and CAT were negatively correlated (P<0.05-0.01), and MDA was positively correlated with BMI (P<0.05). Fitting to the model of multiple stepwise regression of BMI on VC, VE, β-CAR, SOD, CAT, and MDA in 85 OOC was Y = 27.0041 + 0.2541MDA – 2.1448β-CAR – 0.0090CAT, where F = 43.8088, P<0.001, r = 0.7866, r2= 0.6187, adjusted r2= 0.6046. The findings from the reliability analysis for VC, VE, β-CAR, SOD, CAT, and MDA used to reflect increased oxidative stress and potential oxidative damage in the OOC showed that the reliability coefficients (alpha, 6 items) = 0.7231, P<0.0001, and that the standardized item alpha = 0.9207, P<0.0001. Conclusion The present study suggests that there exists an increased oxidative stress in overweight and obese children. Objective To investigate whether overweight and obesity might cause oxidative stress and potential oxidative damage in overweight and obese children in, and to explore its possible mechanism. Methods Eighty-five overweight and obese children (OOC), and eighty-five age-matched healthy children HC) were recruited in this case-control study. The present study studied spectrophotometrically vitamin C (VC), vitamin E (VE), and β-carotene ), catalase (CAT), and the level of malondialdehyde (MDA) in erythrocytes. Results Compared with VC, VE, β-CAR, SOD, CAT and MDA in the HC group, the average values ​​of VC, VE, (P <0.001). The regression analysis demonstrated that VC, VE, [beta] - CAR, SOD, and CAT in the OOC group were significantly decreased CAR, SOD, and CAT were negatively correlated (P <0.05-0.01), and MDA was positively co Fitting to the model of multiple stepwise regression of BMI on VC, VE, β-CAR, SOD, CAT, and MDA in 85 OOC was Y = 27.0041 + 0.2541 MDA - 2.1448 β-CAR- 0.0090CAT, where F = 43.8088, P <0.001 r = 0.7866 r2 = 0.6187 adjusted r2 = 0.6046 The findings from the reliability analysis for VC, VE, β-CAR, SOD, CAT, and MDA used to reflect increased oxidative stress and potential oxidative damage in the OOC showed that the reliability coefficients (alpha, 6 items) = 0.7231, P <0.0001, and that the standardized item alpha = 0.9207, P <0.0001. Conclusion The present study suggests that there exists an increased oxidative stress in overweight and obese children.