In this study, a questionnaire was administered to 634 fathers of preschool children.The results indicated that: (1) father’s involvement and support, child-parent relationship, and preschool children’s social competence were all at the middle level, and there were significant differences across demographic variables such as educational background, average monthly income, residence, and the number of children raised; (2) father’s involvement and support was significant positive correlation with child-parent relationship (r=0.632, p<.001) and preschool children’s social competence (r=0.431, p<.001); while child-parent relationship was positively correlated with preschool children’s social competence (r=0.434, p<.001); (3) structural equation modeling revealed the results: father’s involvement and support significantly predicted child-parent relationship (β=0.737, p<.001) and preschool children’s social competence (β=0.354, p<.001), meanwhile child-parent relationship can significantly positively predict the social competence of preschool children (β=0.169, p<.001); (4) further Bootstrap test shown that child-parent relationship had a significant intermediary effect in the relationship between father’s involvement and support and preschool children’s social competence (95% CI=[0.050,0.387]). The findings suggest that fathers should be mobilized to participate in parenting and provide adequate father support for preschool children to enhance parent-child closeness, mitigate parent-child conflict, and enhance social adaptation and social interaction among children with low social competence.