ObjectiveTo evaluate the levels of physical exercise, mental health and social response in children with autism spectrum disorder (ASD), and explore the mediating effect of social response on physical exercise and mental health. MethodsFrom September, 2019 to April, 2024, 211 children with ASD from three special education schools in Haidian District and Shijingshan District of Beijing were selected. They were assessed with general data questionnaire, Physical Activity Rating Scale (PARS-3), Chinese version of Psycho-Educational Profile (C-PEP) and Social Response Scale-Short Form (SRS-SF). The correlation among physical exercise, mental health and social response was analyzed. The mediating effect of social response on physical exercise and mental health was explored. ResultsThe average physical exercise level was (58.72±3.34), the average mental health level was (14.85±1.67), and the average social response level was (24.98±3.79). Physical exercise was positively correlated with mental health (r = 0.546, P < 0.05) and negatively correlated with social response (r = -0.298, P < 0.05). Mental health was negatively correlated with social response (r = -0.397, P < 0.05). Average monthly family income, parental relationship, repeated transcranial magnetic stimulation therapy, physical exercise, social response were the influencing factors of mental health (P < 0.05). Social response was intermediary between physical exercise and mental health, accounting for 14.56%. ConclusionThe mental health level of children with ASD is poor, and there are many influencing factors. Physical exercise can directly affect the mental health of children with ASD, and can also play an indirect role through social response.