<p>Post-traumatic stress disorder (PTSD) and depression are prevalent forms of psychological distress following persistent natural disasters. The aim of this study was to examine the prevalence and predictors of PTSD, depression, and their comorbidity among adolescents after a severe flood. A sample of 920 adolescent victims of the 2021 Henan flood were recruited from one junior high school. Four months after the disaster, participants completed self-report questionnaires assessing PTSD symptoms, depression, trauma exposure, and childhood trauma. The prevalence rates of PTSD, depression, and their comorbidity were 31.3%, 40.6%, and 22.8%, respectively. Among adolescents with PTSD, 72.8% also had depression, while 56.1% of those with depression also met criteria for PTSD. Left-behind experience, trauma exposure, and childhood trauma were identified as risk factors for PTSD, depression, and their comorbidity. All participants were recruited from a single school, which may limit the generalizability of the findings. Additionally, the absence of pre-disaster baseline data makes it difficult to determine the specific impact of the flood on mental health outcomes. Greater attention and comprehensive interventions should be directed toward adolescents with left-behind experience, a history of childhood trauma, or more severe exposure to the flood in the short term.</p>