Purpose <p>Children with autism spectrum disorder (ASD) tend to be physically less active than their peers. Parents play an important role in their children’s engagement in physical activities. This study adopted network analysis to examine the association between parental beliefs, support, and physical activity in children with ASD and compared the differences in the association patterns between two age groups (6–11 vs. 12–18 years).</p> Methods <p>We surveyed 269 Chinese parents of children with ASD regarding their beliefs, support, and their children’s physical activity. The networks were constructed using the Extended Bayesian Information Criterion Graphical Least Absolute Shrinkage and Selection Operator (EBICglasso) model, and differences between age groups were examined using a Network Comparison Test.</p> Results <p>Supportive parental behaviors of encouragement and perceived ease of participation were identified as key bridge nodes connecting parental beliefs and support with physical activity engagement in children with ASD. The unique bridge node was parent-perceived benefits related to friendships for younger children, whereas parental support was used to explain the benefits of physical activity for older children.</p> Conclusion <p>The research findings indicate that parental encouragement and perceived ease of participation are key factors associated with physical activity in children with ASD.</p>