Objective: To analyze the association of strength quality of junior high school students with comorbid depressive and anxiety (CDA) and its subtypes, so as to provide reference for mental health improvement among junior high students. Methods: A convenient sampling method was used to select 10 007 junior high students aged 13-16 from four cities (Nanchang, Ganzhou, Jiujiang, Shangrao) in Jiangxi Province during September to November 2023. A questionnaire survey and physical fitness tests were employed to collect basic information and assess students depressive and anxiety status, as well as strength quality. The χ 2 test was used to compare the distribution differences of CDA and its subtypes among different demographic characteristics, sleep, physical activity, and overweight/obesity conditions. Logistic regression models were applied to infer the association strength between strength quality and CDA and its subtypes. Results: The overall detection rate of CDA among junior high students was 11.04%. Among the CDA subtypes, the detection rates for mild depression-mild anxiety type, anxiety dominant type, depressiondominant type, and severe depression-severe anxiety type were 3.67%, 3.35%, 0.39% and 3.64%, respectively. Compared to the grip strength and standing long jump scores in the > P 75 group, the risk of CDA occurrence increased in other groups (grip strength: P 25 - P 75 , OR =1.20; < P 25 , OR =1.28; standing long jump: P 25 - P 75 , OR =1.31; < P 25 , OR =1.51; P <0.05). In stratified analysis of different CDA subtypes, compared to the grip strength > P 75 group, the risks for mild depression-mild anxiety type increased in the P 25 - P 75 and < P 25 groups ( OR=1.32, 1.44, P <0.05). Compared to the standing long jump > P 75 group, the risks for anxiety dominant type and severe depression-severe anxiety type increased in other groups (anxiety dominant type: P 25 - P 75 , OR =1.32; severe depression-severe anxiety type: < P 25 , OR =1.87; P < 0.05 ). Conclusions Lower levels of grip strength and standing long jump performance among junior high students are positively correlated with CDA and its subtypes. Lower levels of lower limb strength may be an important predictor of CDA in severe depression and anxiety.