Background:Childhood is important and critical period in human life. The foundation of ego is shaped in childhood. Play therapy is one of the successful strategies to help children with inner conflicts problems. This method of psychotherapy is base on the normal learning processes of children, provides solutions to relieve feelings of stress, and expands self-expression. Group play therapy can enhance the self-awareness, self- regulation, social communication, empathy and adoptability in children.Methods:Present study investigated the effects of play therapy on relational and emotional skills of pre-school children. For this purpose, the total numbers of 372 pre-school children were randomly selected, and divided into two equal groups (case and control). In next step, the BUSSE-SR methodology was used for evaluation and comparison of self-awareness, self-regulation, social interaction, empathy, adoptability, and control groups. Pre-test were performed for both groups and case group was involved in-group play therapy. According to the results of post-test, correlation of variables between case-control groups was examined by multivariate analysis of covariance.Results:Frequency of boys and girls in our sample were 51.3 and 48.7 percent, respectively. The mean age of children was 5.1±0.6 year. According to the results of present study, play therapy significantly enhanced the social-emotional skills (P< 0.001). Our findings are consistent with the results of previous studies in other nations with different environmental and cultural properties. In conclusion, it seems that play therapy can be used in pre-school centers to help children learn problem-solving skills and communicate with others.