〔Abstract〕 Abstract Autism spectrum disorder（ASD）， also known as autism，is a series of neurodevelopmental disorders characterized by social disorders and repetitive stereotyped behaviors/narrow interests. Its pathogenesis is com- plex，and there is a lack of effective treatment drugs，with some cases having adverse outcomes. Recent studies have consistently revealed that individuals with autism spectrum disorder（ASD）commonly exhibit characteristics such as gut microbiota dysbiosis（abnormal Bacteroidetes/Firmicutes ratio）， impaired intestinal barrier function （elevated serum levels of zonulin and LPS），and intestinal immune dysregulation（increased pro-inflammatory cyto- kines including IL-6 and TNF-α), suggesting that gastrointestinal abnormalities may influence central nervous sys- tem development through neuroendocrine，immunoregulatory，and metabolic pathways. Consequently，growing scholarly attention has focused on dietary interventions as potential approaches to alleviate clinical symptoms in children with ASD. This review systematically summarizes the role of gut microbiota and their metabolite altera - tions in ASD pathogenesis，along with recent advancements in understanding the microbiota-gut-brain axis mecha- nisms. Additionally ，it elaborates on the therapeutic effects and underlying biological basis of restrictive diet therapy，modified diet therapy，and nutritional supplementation therapy in promoting the health of children with ASD. This systematic review reveals that children with ASD exhibit significant gut microbiota dysbiosis（e. g. ，in- creased Clostridium，decreased Faecalibacterium）and abnormal metabolite profiles（e. g. ，altered short-chain fatty acid spectra，elevated 4EPS levels）. These alterations exacerbate neuroinflammation and immune dysregula- tion through the microbiota-gut-brain axis，thereby impacting nervous system development and function. Further- more，interventions such as ketogenic diets，camel milk，and specific nutritional supplements can alleviate certain ASD symptoms by modulating gut microbiota，restoring intestinal barrier function，and improving metabolic path- ways. Future investigations should aim to create multi-omics evaluation systems for pinpointing potential beneficia- ries，devise individualized intervention strategies rooted in microbiome characteristics，and verify their therapeutic value and safety in large-scale randomized controlled trials. These efforts are crucial to transitioning ASD treatment from symptomatic control to address disease etiology，thereby paving the way for improving prognoses.