Background: In 2021, a once-in-a-century heavy rainstorm suddenly attacked Zhengzhou, an important inland city in northern China. However, there have been no studies on the psychological health of disaster-stricken residents. This study is the first to comprehensively report on the mental health status and related factors of local ordinary residents after the heavy rainstorm. Objective: The purpose of this study is to investigate the mental health status and related influencing factors of local ordinary residents after the flood disaster, and to provide reference for government departments to formulate disaster psychological intervention countermeasures based on evidence-driven strategies. Methods: The snowball sampling technique was used in this study, and measurement tools of Rainstorm Exposure Questionnaire, Subjective Perception of Rainstorm, Post-Traumatic Stress Disorder Checklist-Civilian version (PCL-C), Depression, Anxiety and Stress Scale-21 (DAS-21) and Chinese version of Social Support Rating Scale (SSRS) were used to evaluate the rainstorm exposure, subjective perception of the rainstorm, psychological symptoms and social support of the disaster-stricken residents within a week after the rainstorm. Logistic regression analysis was used to examine the psychological status and related factors of local residents after the rainstorm disaster. Results: A total of 469 valid samples were obtained in this study. All the subjects were in the disaster area and experienced the rainstorm personally, with normal intelligence. The statistical results showed that 25.37% people had experienced at least three rainstorm-related stresses, nearly 20.26% people had post-traumatic stress disorder (PTSD) symptoms, and 39.3%, 53.92% and 65.83% people had depression, anxiety and stress symptoms, respectively. Multivariable logistic regression analyses indicated that female (all p < 0.05), the divorced, agricultural workers/farmers (all p < 0.05), students (all p < 0.05), people experiencing at least three rainstorm-related stresses (p < 0.05 or p < 0.01), people with lower satisfaction at the social flood fighting measures (p < 0.05 or p < 0.01) and people with low social support (p < 0.05 or p < 0.01) were all independent risk factors for poor psychological health, and college education or above (p < 0.05 or p < 0.01), the lower degree of worrying about themselves (all p < 0.01), family members (all p < 0.01) and family property (all p < 0.01) were all related to higher psychological health among flood survivors after the disaster. Conclusions: Rainstorm could cause local residents to have various degrees of psychological symptoms. This study identified factors associated with the psychological health of disaster-stricken residents, which could be used to develop psychological interventions in improving psychological health of local residents. [ABSTRACT FROM AUTHOR]