Introduction: This study aimed to meta-analyze the influential play therapy studies on behavioural disorders in children in Iran. Method: The analysis of the present research method uses internal and external databases to find and collect all research reports. The sample used included 22 studies conducted from 1997 to 2013, including 637 subjects. The data from these 22 studies were meta-analyzed by the standardized effect size difference method or Cohen d for the fixed effects model. All statistical operations were performed using the second edition of comprehensive meta-analysis software. Results: The results showed that the average effect size of the studies is 0/434 for the fixed effects model and 0/477 for the random effects, both of which are significant. Because the effect sizes were heterogeneous, moderators were searched. The results showed no significant difference between the effect size of the studied studies according to the research design and the gender of the subjects. However, there was a substantial difference between the effect of studies on the effectiveness of play therapy on children's behavioural disorders according to the subject's age, the type of independent variable and the number of play therapy sessions. Conclusion: Holding play therapy sessions ultimately and in multiple sessions and at a young age can improve more behavioural disorders in children.