ABSTRACT The present study explored the effect of family functioning on secondary vocational students’ problematic behavior, and the mediating roles of positive psychological traits (hope, gratitude and grit). A total of 3049 secondary vocational students (15.87 ± 1.00 years old) participated in the current research by completing measures of family functioning, problematic behavior, hope, gratitude and grit. The results indicated that family functioning was negatively correlated with problematic behavior. Secondary vocational students from families with better functioning exhibited less problematic behavior. Furthermore, structural equation analysis revealed that hope, gratitude and grit played parallel mediating roles in the association between family functioning and problematic behavior. Pairwise contrasts suggested grit exerted strongest indirect effect among the three mediators. The current research highlighted the role of positive psychological traits in the comprehension of how family environment affects behavioral development among adolescents from secondary vocational school.