Purpose: The purpose of this study was to explain a structural model of posttraumatic growth among psychiatric nurses based on existing models and a literature review and verify its effectiveness. Methods: Data were collected from psychiatric nurses in one special city, four metropolitan cities, and three regional cities from February to March 2016. Exogenous variables included hardiness and distress perception, while endogenous variables included self-disclosure, social support, deliberate rumination, and posttraumatic growth. Data from 489 psychiatric nurses were analyzed using IBM SPSS Statistics 19.0 and AMOS 20.0. Results: The modified model was a good fit for the data. Tests on significance of the pathways of the modified model showed that nine of the 14 paths were supported, and the explanatory power of posttraumatic growth by included variables in the model was 69.2%. For posttraumatic growth among psychiatric nurses, deliberate rumination had a direct effect as the variable that had the largest influence. Indirect effects were found in the order of hardiness, social support, and distress perception. Self-disclosure showed both direct and indirect effects. Conclusion: A strategy to improve deliberate rumination is necessary when seeking to improve posttraumatic growth among psychiatric nurses. Enhancing psychiatric nurses’ hardiness before trauma would enable them to actively express negative emotions after trauma, allowing them to receive more social support. This would improve deliberate rumination and consequently help promote psychological growth among psychiatric nurses who have experienced trauma.