Separation anxiety is a kind of disorder that has a direct relationship with parenting style. Family based intervention and play therapy is a comprehensive program including training sessions for parents which focus on improving interpersonal relationships, establishing a healthy and positive interaction in the family, controlling family anger, investigating communication barriers in marital relationships, educating children and providing play therapy for children. Objective of the present study was to investigate the effectiveness of family based intervention and play therapy in parenting style and stress of mothers and clinical symptoms of children with separation anxiety disorder.   Present research is a semi-experimental study in which there were two groups of 14 subjects along with pre-test and post-test.   Statistical population of the present study included all clients of a counseling centers in Tehran city who has been diagnosed with separation anxiety disorder. Therefore, to select some samples, availability sampling method was used.  Analysis of the research data with multivariate covariance analysis method showed that there was a significant difference between the parenting style and stress of mothers and clinical symptoms of children with separation anxiety disorder in both experimental and control group. This intervention had a significant effect on the parenting style of mothers and the reduction of parenting stress and it also reduced clinical symptoms in children with separation anxiety disorder.