Traumatic life experiences such as earthquakes are impactful on individuals' mental health and positive psychological characteristics are key assets for the preservation of mental health after stressful situations. Strength-based parenting and optimism are considered among those strengths to combat psychological problems including depression. The current study aimed to examine the longitudinal mediating effects of optimism between strength-based parenting and depression (model 1) and post-traumatic growth (model 2). Participants included 137 university students ranging in age between 18 and 53 (M = 21.83, SD = 5.41). Results demonstrated that strength-based parenting at baseline significantly and negatively correlated with depression while positive correlations were found with optimism and post-traumatic growth at a six-month follow-up. Moreover, optimism (T2) mediated the relationship between strength-based parenting (T1) and depression (T2) and post-traumatic growth (T2). Thus, this study identified the positive qualities and strengths to combat the adverse psychological effects of traumatic experiences including earthquakes, and deepened the current understanding of how strength-based parenting longitudinally contributes to individuals' positive psychological strengths, processes, and mental health after "the disaster of the century."