This study examined the mediating role of perceived severity of trauma and rumination in the relationship between traumatic experiences and PTSD, and assessed the moderated role of resilience in this mediating process. Nine hundred and fifty-one adolescents were selected to complete a self-report questionnaire involving rainstorm-related experiences, perceived severity of trauma, rumination, resilience, and PTSD. The results found that rainstorm-related experiences had a positive effect on PTSD by perceived severity of disaster, or by rumination via perceived severity of disaster. Resilience buffered the relationship between rainstorm-related experiences and PTSD, but did not buffer the relation of rainstorm-related experiences to perceived severity of disaster and rumination. These findings indicated that rainstorm-related experiences may have an indirect effect on PTSD via cognitive activities, and these indirect paths were not buffered by resilience. A buffering effect only occurred in the direct paths from rainstorm-related experiences to PTSD.