Behavioral disorders are one of the most common psychological issues of childhood and adolescence. The aim of the present study was to examine the effect of family-based intervention program on parenting skills of mothers and clinical symptoms of children with behavioral disorder. The study was quasi-experimental research. The population all students with behavioral disorders who were studying the first to six grades in this study, sixthy students and along with their parents were selected as the main sample of the research. The research tools included Baumrind's parental style inventory and clinical symptoms checklist. The intra-family relationships promotion program was held as eight group sessions for parents, an individual family session, two phone- call sessions and an enforcement session. The research findings indicated that the family-based intervention program could improve mothers' authoritative parenting skills and also could reduce clinical symptoms of children and the results were stabled for a three-month follow-up. Therefore, family and child counselors can use this family-based intervention program to increase parenting skills of mothers and reduction clinical symptoms of children with behavioral disorder.