Objective: To analyze the influence of stress and psychological resilience on the dietary behavior of middle school students so as to privide a basis for the development of policies and interventions aimed at improving middle school students dietary behavior. Methods: A total of 8 874 middle school students in Shanghai were surveyed using stratified cluster random sampling method from November 2019 to January 2020. The questionnaire included general information, dietary behavior, Perceived Stress Scale (PSS-10) and Connor-Davidson Resilience Scale (CD-RISC-10). Factor analysis was used to analyze the dietary behavior model. Logistic regression model was used to explore the correlation between stress, psychological resilience and dietary behavior in adolescents. Besides, a structural equation model was established to analyze the mediating effect of psychological resilience on stress and dietary behavior. Results: The total score of psychological resilience among middle school students was (27.99±9.83), and the total score of stress was (25.56±7.06). Factor analysis categorized dietary behavior into two types: the high energy dietary behavior and balanced dietary behavior. High energy dietary behavior exhibited statistically significant differences across genders and schooling stage ( χ 2=41.37, 204.03), while balanced dietary behavior showed statistically significant differences across schooling stage and socioeconomic status ( χ 2=130.23, 96.53) (all P <0.01). Logistic regression analysis showed that adolescents with moderate and high stress levels had an increased risks of high energy dietary behavior ( OR=1.25, 95%CI =1.12-1.39; OR=1.58, 95% CI = 1.39-1.79) and a reduced likelihood of reduced balanced dietary behavior ( OR=0.73, 95%CI =0.65-0.81; OR=0.53, 95%CI =0.47-0.60); adolescents with high levels of psychological resilience had a decreased risk of highenergy dietary behavior ( OR= 0.73 , 95%CI =0.65-0.83), and those with moderate and high resilience levels showed improved balanced dietary behavior ( OR= 1.45 , 95%CI =1.29-1.62; OR=2.50, 95%CI =2.21-2.84) (all P <0.01). The mediating effect of psychological resilience between stress and high energy dietary behavior or balanced dietary behavior accounted for 15.61% and 56.10% of the total effects, respectively. Conclusions Stress and psychological resilience are the influencing factors of dietary behavior in middle school students. Psychological resilience have a partial mediating effect between stress and high energy dietary behavior or balanced dietary behavior.