BackgroundIt is unclear about the mutual impact of COVID-19 related psychological stress and infection on mental health of adolescent and youth students. This study aimed to explore the mutual impact of COVID-19 related psychological stress and infection on mental health problems among students. MethodsThis study was conducted from December 14, 2022 to February 28, 2023 in Sichuan, China. Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, PTSD Checklist for DSM-5, Insomnia Severity Index, and Internet Addiction Test were used. Participants were grouped by COVID-19 infection and psychological stress level. The differences among groups were compared, and logistic regression analysis was used to investigate risk factors for depression, anxiety, PTSD and insomnia among groups. ResultsOf 90,118 participants, 82,873 (92.0 %) finished the questionnaires and were included in the study. Of 82,873 participants, 33,314 (40.2 %) reported to be infected with COVID-19. Participants had depression symptoms (38.1 %), anxiety symptoms (31.8 %), PTSD (33.9 %), insomnia (34.0 %), and internet addiction (60.3 %). Compared with participants uninfected with low psychological stress level, the risk for symptoms of depression, anxiety, PTSD and insomnia increased by 9.6 %, 12.3 %, 6.6 %, and 12.0 % in participants infected with low psychological stress level (p < 0.001), 106.8 %, 125.9 %, 125.2 %, and 95.7 % in participants uninfected with high psychological stress level (p < 0.001), and 147.3 %, 161.1 %, 158.7 %, and 141.0 % in participants infected with high psychological stress level (p < 0.001). LimitationThis study is a cross-sectional design, and no causal associations should be inferred. Infection status was based on self-report of participants with infectious symptoms. ConclusionCOVID-19 related psychological stress and infection per se have mutually overlapping impacts on mental health problems among students. Further health policies and psychosocial interventions should be developed to reduce mutually overlapping impact and improve the long-term mental health among students.