The purpose of this study was to investigate the effect of group art therapy using refractory techniques on children's self-expression and peer relationships. The subjects of the study were 14 children aged from 6 to 7, and after a homogeneity test was conducted, seven of the children were placed in the experimental group and seven in the control group. Regarding the research tool, researchers conducted a total of 12 sessions of group art therapy using self-expression tests, peer relationships tests, and refractory techniques from December 7, 2019, to February 29, 2020. For the data analysis, t-test was conducted to verify the homogeneity of the experimental group and the control group, and repeated measurement variable analysis was conducted. The results were as follows. First, in the case of the experimental group, the content part, which is a sub-area of self-expression, showed a positive change. Second, in peer relationships, positive changes occurred in sociality, leadership, competence, and cooperation. However, stability did not show a significant difference compared to other sub-areas, and later scores improved slightly. On the other hand, in the case of the control group, no significant difference emerged between the pre-and post-assessment scores. The research results showed that collective art therapy using refractory techniques positively affected children's self-expression and peer relationships. Based on these research results, the significance and limitations of this study were then discussed.