This study aimed to evaluate the effects of applying sensory integration therapy on the peer interaction of siblings with children with disabilities. These subjects were preschool children aged between 3 and 7 years who had used the child development center. A total of 20 children were recruited, 10 for the experimental and control groups. Then, 10 healthy siblings of children with disability supported the experimental group and compared with the control group. The sibling sensory integration therapy was performed in the experimental group, whereas individual sensory integration therapy was conducted in the control group. The treatment was administered once a week for a total of 10 weeks, 40 min per session, and 10-min interview with the children's parents. Based on the theory of sensory integration therapy, play that meets the neurological needs of each child was selected and provided. The total score is 0-96 points, indicating that the higher the score, the more negative peer interactions, and that the lower the score, the more positive the peer interactions. Among them, 22–29 and 31 questions were scored in reverse because they meant that the lower the score, the more negative the interactions. This tool is divided into three subcategories: play disruption (13 questions), disconnection (11 questions), and interaction (8 questions). A significant difference was confirmed in the area of play disruption in the experimental group and total scores; however, no significant difference was observed in the other areas. When sensory integration therapy intervention was applied to children with disability and their siblings, it was more effective within the play disruption area of peer interaction than in children with disability without a sibling.