Objectives: The purpose of this study was to examine whether demographic and socio-economic characteristics, health behaviors are related overweight and obesity in Korean adolescents. Methods: Data from the 15th Korea Youth Risk Behaviors web-based Survey(KYRBWS) administered in 2019 were analyzed: 60,100 students in middle and high school participated in the survey. But except 1,555 missing value, 55,748 students were analyzed. It was conducted frequency analysis, Rao-Scott chi-square test and multiple logistic regression analysis. Results: The significant influencing factors on overweight and obesity of adolescents were gender, economic status, father’s educational background, alcohol experience, fastfood consumption, muscle strengthening exercise, stress perception(p<.001). The odds ratio for overweight and obesity of male adolescents compared to female adolescents were 1.19(p<.001). and The odds ratio for overweight and obesity of perceived stress adolescents compared to those who without stress were 1.13(p<.001). Conclusions: I found that adolescents’ some undesirable health behaviors affect their overweight and obesity, I recommend that school health promotion programmes should be implemented in schools to form good health behaviors such as healthy eating habits, physical exercise and managing stress.