Background <p>Attention deficit hyperactivity disorder (ADHD) is a common clinical developmental disorder. Aerobic exercise effectively improves the inhibition function of ADHD children, but its intervention mechanism is not clear yet. This study aimed to explore the brain mechanisms of aerobic exercise improving inhibitory function in children with ADHD.</p> Methods <p>20 school-age children with ADHD were studied. Before and after swimming exercise three times a week for 8 weeks, resting-state functional magnetic resonance imaging (rs-fMRI) and Flanker task tests were performed respectively. fMRI analysis focused on the right inferior frontal gyrus (rIFG), and the whole-brain functional connectivity (FC) was calculated based on rIFG. Paired t-test was used to analyze the FC value and the behavioral results of the Flanker task. And the correlations between the FC and the behavioral changes before and after swimming exercise were analyzed.</p> Results <p>This study found that the brain regions with significant differences in rIFG-based FC values included rIFG, right inferior parietal lobule, and cerebellum posterior lobe. The response time after exercise was significantly shorter than that before exercise, while the accuracy after exercise was higher than before. And, the FC changes within rIFG were negatively correlated with the response time changes and positively correlated with the accuracy changes of the Flanker task.</p> Conclusion <p>This study suggests that the FC within rIFG and the FC between rIFG and right inferior parietal lobule are related to the improvement of inhibition function in ADHD children.</p>