The purpose of this study was to investigate the mediating effect of adaptive cognitive emotion regulation strategies on the posttraumatic growth of optimism in Christian university students. For this purpose, 205 Korean Christian university students were studied, the results were analyzed using the structural equation model. The result showed that optimism, posttraumatic growth, and adaptive cognitive emotion regulation strategies showed a significant positive correlation with each other. In other words, the more optimistic people are, the more they experience positive change and growth after trauma, and use the adaptive cognitive emotion regulation strategies better. Second, adaptive cognitive emotion regulation strategies were found to be mediated in the effect of optimism on posttraumatic growth. This implies that optimism affects posttraumatic growth through adaptive cognitive emotion regulation strategies. Based on the results of this study, this study suggests the implications of Christian counseling.