Objective To understand the current situation and influencing factors of overweight and obesity among high school students in Ninghai County,Zhejiang Province,and to provide scientific basis for the prevention measures of overweight and obesity among high school students. Methods Using stratified cluster random sampling method,height and weight measurement and questionnaire survey were conducted among high school students in Ninghai County,Chi-square test and unconditional logistic regression model were used to analyze the influencing factors of overweight and obesity. Results A total of 2 419 high school students were surveyed,with an overweight and obesity rate of 24.68%.The overweight and obesity rate was higher in boys than that in girls (χ²=49.415,P<0.001).Multivariate logistic regression analysis showed that the factors affecting the overweight and obesity rate of high school students included:male(OR=1.712,95%CI:1.367-2.144),birth weight>4 000 g(OR=2.211,95%CI:1.225-3.990),parents were obese (OR=4.513,95%CI:3.016-6.753),picky eaters(OR=0.699,95%CI:0.565-0.865),fast eating speed(OR=3.191,95%CI:1.677-6.073),meat and vegetable with heavy meat(OR=2.833,95%CI:1.604-5.001),occasionally or no breakfast during the week(OR=1.504,95%CI:1.055-2.142),drinking sugar-sweetened beverages≥4 times a week (OR=1.325,95%CI:1.001-1.753),daily outdoor activities<2 hours(OR=1.516,95%CI:1.178-1.950) and no naps (OR=1.294,95%CI:1.050-1.595). Conclusion The prevalence of overweight and obesity among high school students in Ninghai County is relatively high,and relevant departments should take targeted intervention measures to prevent the occurrence of overweight and obesity among high school students.