The main purpose of this study was to explore the peer interaction of two single children, and to research roles that the adults played in children's peer interaction. The study used qualitative and case study approach to observe two single children's interaction. In addition, researchers interviewed the children's parents and teachers to collect relevant data. The results of this study were as followings:1. Two single children's peer interaction were developed and varied in a preschool classroom.2. The family members were the pushers for single children's peer interaction.3. The teachers of two single children were supporters and reminders when facing the single children's peer interaction.According to the results, the recommendations were provided to preschool teachers and future research.