["Autism Research, EarlyView. ", "\nABSTRACT\nAutistic children placed in regular classrooms are frequently exposed to peer exclusion, yet the mechanisms underlying the impairment of their prosocial behavior remain unclear. The mediating role of inhibitory control warrants urgent investigation. This study aims to explore the mechanisms through which peer exclusion influences prosocial behavior in autistic children placed in regular classrooms, paying specific attention to the mediating role of inhibitory control. Convenience sampling is used to recruit autistic children placed in regular classrooms from several cities in Guangdong Province, China. A cross‐validation approach combining a questionnaire survey (Study 1, N = 158) and an experimental design (Study 2, N = 128) is used to assess children's perceived peer exclusion, inhibitory control, and prosocial behavior. Results show that peer exclusion not only negatively predicts autistic children's prosocial behavior directly, but also indirectly weakens prosocial performance by depleting their inhibitory control resources. Inhibitory control partially mediates this relationship, accounting for 16.32% (Study 1) and 29.10% (Study 2) of the mediating effect, respectively. These findings reveal the underlying pathway through which peer exclusion influences social behavior in autistic children from the perspective of cognitive resource depletion, providing empirical support for intervention models integrating environmental support and cognitive training in inclusive education.\n"]