The purpose of this study is to determine the degree of regular children’s knowledge on social interaction of children with autism found in inclusive school. This research used quantitative descriptive method. The data collected through questionnaire. The subject of this research is 5 reguler students from one inclusive private school in Surakarta City.The results of the questionnaire were processed by using a scoring system that has been validated by expert in the form of scale and percentage of knowledge. The conclusion of this study is that 40% of regular children have fair knowledge to the social interaction of children with autism and 60% still have slight knowledge.