Autism spectrum disorder requires early detection and treatment. Thus, we developed a method to obtain reliable neurophysiological biomarkers to assist in diagnosing autism. This method includes a simple but typical jigsaw puzzle that allows participants to play and interact with each other. While playing this game, brain signals of the participants were observed and analyzed. The patients with autism were found to have differences in the time range of some event-related potential, such as P300 and N400. Altered patterns of function connectivity were also found in delta frequency bands in the patients while interacting with other people. Working around patients' capabilities, the jigsaw puzzle game was designed as easy to complete; this caused fewer mismatch conditions. The result suggested that these patterns are promising neurophysiological biomarker to assist doctors in social cognitive assessment in autism.Clinical Relevance-This study demonstrated the possibility of using hyperscanning technique for social cognitive assessment of autism spectrum disorder.