Childhood is a critical period for the development of prosocial behavior, and the family serves as a crucial microsystem for fostering prosocial behavior in children. Prior research has indicated that parental monitoring, a specific family factor directly targeting children, can predict children's prosocial behavior. However, the influence of the overall family climate on children's prosocial behavior remains unclear. This study focuses on different levels of family factors and examines the dynamic longitudinal effects of both parental monitoring and family conflict, simultaneously, on children's prosocial behavior. Three-wave data from 4,691 children (M[subscript baseline age] = 9.480, SD = 0.507; 48.2% female) in the ABCD database were analyzed. The results of the cross-lagged panel model revealed significant longitudinal mutual predictive relations among family conflict, parental monitoring, and children's prosocial behavior. After disentangling between-person associations, the findings from the random-intercept cross-lagged panel model showed that increasing parental monitoring consistently predicted future increases in child prosocial behavior from childhood to early adolescence, and reducing family conflict significantly predicted future increases in prosocial behavior during early adolescence. These findings underscore the importance of considering not only specific family factors that directly target the child, but also holistic family factors such as family conflict in shaping positive child development.