Objective: To improve the self-harmony and dormitory interpersonal relationship quality of college students. Methods: College students (15 in the experimental group and 15 in the control group) were recruited for group sandplay intervention, and the Self-Harmony Scale, Psychological Boundary Scale and Interpersonal Relationship Questionnaire were filled in before and after the intervention, and the sand table content record form, sand table theme characteristic analysis form and sand table unit feedback form were used to record the experimental process. Results: With the advancement of group sand table intervention, the participants’ sense of belonging, autonomy and competency in the group were significantly improved. The theme of trauma in the sand table works decreased, and the theme of healing increased, gradually becoming more neutral and integrated. According to the paired sample t-test, the psychological boundary (t=-2.76, p<0.05) of the experimental group was significantly thinner, the score of self-experience disharmony (t=2.53, p<0.05) was significantly decreased, and the score of flexibility (t=-2.29, p<0.05) was significantly improved. The total score of dormitory relationship (t=-5.52, p<0.001) and the scores of verbal communication, disturbing behavior, sharing behavior, and personality factors were significantly improved. Conclusion: As a psychological technique, group sandplay is widely used in school psychological education, which can effectively improve college students’ self-harmony and interpersonal relationship in dormitory.