Autism spectrum disorder (ASD) is a common severe, clinically and genetically heterogeneous childhood-onset neurodevelopmental disorder. Due to its high prevalence, typical autistic symptoms, and severe lifelong impairment without effective prevention and treatment, the developmental change of brain functions in individuals with this study has been recognized as one of the key topics of ASD. The goal of this project is to prospectively investigate the stability and changes of brain functions assessed by neuropsychological tests and neuroimages in a cohort of children and adolescents with ASD who had the first assessment 3-5 years ago.