Objectives This study was performed to investigate the effects of obesity, food, physical activity and stress on blood pressure changes for children and for adolescents. Methods The participants were the first and the fourth grade elementary school students and the first grade of middle school students. They were asked to measure the blood pressure, height, weight and were asked to complete questionnaires. Results The systolic and diastolic blood pressure of male was significantly higher than that of female and the prevalence of hypertension among the first and the fourth grade elementary school students and the first grade of middle school students were 15.6%, 13.6%, and 7.8%, respectively. Height, weight and body mass index (BMI) were highly correlated with the level of blood pressure. However, food, and physical activity, stress and depression were poorly correlated with the level of blood pressure. Conclusions This study proved that blood pressures in children and in adolescent were closely related with obesity, sex, and height.