Background: The incidence of autism spectrum disorder (ASD) is still on the rise worldwide. Tai Chi fan is considered a non-pharmacological treatment with potential benefits for the treatment of ASD. However, there is currently insufficient evidence to support this claim. Objective: This study aims to determine the efficacy and safety of Tai Chi fan in improving ASD, and explore its possible impact on intestinal microecology. Methods: Based on a Randomized Controlled Trial (RCT) design and a gut microecology analysis program, this study recruited 40 children with ASD and randomly assigned them to either a Tai Chi fan group or a control group. The intervention consisted of eight weeks of Tai Chi fan exercise and rehabilitation as standard treatment, followed by a two-week follow-up. The primary outcome was autism severity secondary outcome was the assessment of autism and its related symptoms using the Childhood Autism Rating Scale (CARS), Social Responsiveness Scale (SRS), and Autism Behavior Checklist (ABC). All above scales with higher scores indicating a greater degree of autism. The Test of Gross Motor Development, Third Edition (TGMD-3) was used to evaluate gross motor development, with higher scores indicating better gross motor development. The study also collected 16s rDNA intestinal microecology samples to explore the association between the structure and function of gut microecology and the effect of Tai Chi fan exercise. Overall, the study aims to fully leverage the clinical and intestinal microecology data to assess the clinical effectiveness of Tai Chi fan exercise on autism spectrum disease. Discussion: We believe that the results of this study will enhance our comprehension of how Tai Chi fan exercise influences the clinical symptomatic manifestations linked with ASD and changes in intestinal micromorphology. These insights could potentially fortify the clinical evidence supporting the use of Tai Chi fan exercise in treating patients with ASD.