Objective: To understand trends and related factors influencing overweight and obesity among primary and secondary school students in Tianjin, so as to provide a basis for formulating overweight and obesity prevention and control strategies. Methods: In September of each year from 2019 to 2023, a survey was conducted among 197 707 primary and secondary school students in 16 districts of Tianjin through a stratified random cluster sampling method. Physical examination was carried out in accordance with the Technical Standard for Physical examination for Student, and overweight and obesity survey was carried out. Basic information, smoking, drinking, diet, physical exercise, and sleep status were collected through questionnaire surveys. Results: The detection rates of overweight and obesity among primary and secondary school students in Tianjin from 2019 to 2023 were 39.07%, 43.33%, 41.54%, 43.92%, and 40.24%, respectively，showing an increasing trend(χ2trend=7.96,P<0.01). The detection rates of overweight increased in both vocational high schools and suburban counties (χ2trends=9.08, 47.18, P<0.01). The detection rates of obesity increased among both male and female students, in primary and vocational high schools and suburban counties (χ2trends=108.34, 15.99, 7.32, 10.95, 14.75, P<0.01). Multivariate Logistic regression analysis showed that smoking, drinking, unhealthful diet, and lack of proper physical exercise had a higher risk of obesity among primary and secondary school students (OR=1.26, 1.13, 1.08, 1.21, P<0.05). Stratified analysis showed that the risk of obesity was higher among boys with unhealthful and moderate lifestyle habits, as well as primary school students with unhealthful lifestyle habits (OR=1.15, 1.11, 1.27, P<0.05). Boys, girls and primary school students with unhealthful lifestyle habits, girls and ordinary high school students with moderate lifestyle habits had higher risk of being overweight (OR=1.14, 1.32, 1.21, 1.18, 1.40, P<0.05). Conclusions The detection rates of overweight and obesity among primary and secondary school students in Tianjin shows an increasing trend. Comprehensive lifestyle should be implemented to better prevent and control the risk of overweight and obesity.