Objective: To investigate the tendency of obesity and depressive symptoms in middle school students in Tianjin, so as to provide a reference for exploring the clustering patterns of health risk behaviors and their effects on obesity and depressive symptoms. Methods: A stratified cluster sampling method was used to investigate the obesity, depressive symptoms and health risk behaviors of middle school students from 16 counties of Tianjin from 2019 to 2023. The latent classes analysis was used to classify health risk behaviors. The χ 2 test and Logistic regression were used to analyze the effects of different categories on obesity and depression symptoms. Results: The obesity detection rate of middle school students in Tianjin from 2019 to 2023 first increased ( 20.90% in 2019, 23.35% in 2020) and then decreased and gradually stabilized (2021-2023:22.20%-22.69%), and the detection rate of depressive symptoms showed a decreasing trend (from 21.65% to 14.92%). The detection rate of comorbidity of obesity and depressive symptoms first increased (4.62% in 2019, 4.66% in 2020) and then gradually decreased to 3.43% in 2023, and the rate was higher in boys than in girls and higher in urban areas than in suburban areas. Latent category analysis classified health risk behaviors into four categories: lack of exercise group, poor behaviors such as sleep group, poor diet group and healthy group. After adjusting for demographic characteristics,the results of Logistic regression analysis showed that the co-occurrence risk of obesity and depression symptoms among the top three groups of middle school students were 1.35( OR=1.35, 95%CI =1.15-1.58), 4.20( OR=4.20, 95%CI =3.50-5.04), and 1.84( OR=1.84, 95%CI =1.40-2.38)times, compared to the healthy group ( P <0.05). Conclusions From 2019 to 2023, the comorbidity rate of obesity and depression among middle school students in Tianjin increased first and then decreased gradually. Interventions should be made in the aspects of exercise, diet, sleep and other behaviors.