AbstractThe main purpose of conducting this study was to investigate the effectiveness of group play therapy in preschool children’s creativity and aggression control. The research method was experimental along with pretest-posttest design in control group.The sample of study included all preschool students of Dehloran town with a total number of 60 students from preschool students that (30 subjects in experimental group and 30 subjects in control group) were selected by multistage random cluster sampling. The research instruments were Torrance’s creativity questionnaire and aggressiveness questionnaire of Shahim. Their reliability and validity have been confirmed and to analyze the findings, covariance analysis test was used. The major findings of the research indicate that, group play therapy in preschool children’s creativity and aggressionhas a significant effect on the level of 0.01 and it enhances creativity and reduces aggression in preschool children.