Exploring the mental health level and influencing factors of rural middle school students, andcomparing the differences in mental health levels between left behind and non left behind middle schoolstudents, providing basis and reference value for the prevention and intervention of mental health amongrural left behind middle school students. This study used the Anxiety and Depression Scale, Core SelfAssessment Scale, Psychological Resilience Scale, Social Support Rating Scale, and Family EnvironmentScale to investigate the mental health level, personal traits, and environmental support of 3, 085 ruralmiddle school students. The results show that: (1) The overall mental health level of rural middleschool students is relatively low, with a depression detection rate of 57.54% and an anxiety detectionrate of 37.34%. Girls have significantly higher scores of anxiety and depression than boys, and thereis no significant difference in scores between left behind and non left behind middle school students;(2) Core self-evaluation, psychological resilience, social support, and family environment intimacy are allsignificantly negatively correlated with anxiety and depression. The psychological resilience of left behindmiddle school students is significantly lower than that of non left behind middle school students, butthere is no significant difference between the two groups in terms of core self-evaluation, total score ofsocial support, and intimacy of family environment; (3) Regression analysis showed that the combinationof core self-evaluation (-0.567), psychological resilience (0.054), social support (0.111), and familyenvironment intimacy (0.190) can predict 52.9% of the variance in anxiety levels. The combination of coreself-evaluation (-0.357), psychological resilience (-0.305), social support (-0.174), and family environmentintimacy (-0.089) can predict a 60.2% variance in depression levels. The above results indicate that theoverall mental health level of rural middle school students is poor, and the predictive degree of core selfevaluationon the variability of anxiety and depression is higher than the sum of other factors. Therefore,core self-evaluation may be one of the key factors to protect the mental health level of rural left behindmiddle school students.