Abstract: The digestive system is one of the nine major systems of the human body and is an important system for the body to obtain and absorb nutrients. The gastrointestinal tract is the part where food is decomposed and absorbed, and the intestinal flora is distributed in different parts of the gastrointestinal tract, participating in the composition of the gastrointestinal system, which is conducive to the homeostasis of the intestine, while synthesizing some substances needed by the human body, playing a role in the digestion and absorption of food. The various substances synthesized by the intestinal flora play a role in the maintenance of the intestinal barrier, the suppression of intestinal inflammation, the human immune system, and neurodevelopment. In recent years, the incidence of autism spectrum disorders has shown an increasing trend year by year, and the comorbid diseases that accompany children with autism have also attracted the attention of scholars. Gastrointestinal disease is one of the common comorbid diseases in children with autism spectrum disorder, and many ASD children had diarrhea, constipation and other gastrointestinal diseases.However， the specific mechanism by which gastrointestinal disorders occur in ASD children is unclear. Studies have found that changes in the level of short-chain fatty acids produced by the intestinal flora in the intestine can affect the core symptom performance of ASD children.This finding has attracted the attention of scholars, and provides a new idea for the mechanism research and prevention of comorbid gastrointestinal diseases in ASD children. This article reviews the mechanisms by which short-chain fatty acids produced by intestinal flora affect the core symptoms of autism spectrum disorder.

Key words:

Autism spectrum disorder, Core symptoms, Blood brain barrier, Short-chain fatty acids, Intestinal flora