Objectives: This study was performed to determine the relationship between abnormal liver function and metabolic risk factors in obese children and adolescents. Methods: The participants were 118,830 obese children and adolescents who received health examinations for students supervised by Korean Ministry of Education and conducted by the Korea Association of Health Promotion in 2006-2015. Obesity were evaluated by relative weight, and the metabolic risk factors consisted of blood pressure, fasting blood sugar, and total cholesterol. ‘Abnormal liver function’ was defined by ALT and AST. The association of ‘Abnormal liver function’ with metabolic risk factors were explored after adjusting for sex and grade of school, by using multivariate logistic regression analysis. Results: The factors significantly associated with abnormal liver function were degrees of obesity, blood pressure, fasting blood sugar, and total cholesterol. Severe obesity had highest odds ratio of 4.92 (95% Confidence Intervals, 4.66-5.20; pqqqlt;.001) among the metabolic risk factors. Conclusions: Metabolic risk factors had a significant impact on abnormal liver function. In order to prevent non-alcoholic fatty liver disease in obese children and adolescents, it is most important to lose weight and it is also necessary to manage risk factors through regular health examinations and lifestyle intervention.