Abstract: There has been a controversy as to whether exogenous γ-aminobutyric acid can enter brain regions. The concept of "microbe-gut-brain axis" suggestes that exogenous γ-aminobutyric acid is able to enter the body through oral administration. The γ-aminobutyric acid is subsequently involved in the regulation of gastrointestinal microenvironment, which benefits the central system and provides treatment for neurological diseases. Currently, the γ-aminobutyric acid prepared by microbial method can be used as a new food raw material in certain foods and functional foods rich in γ-aminobutyric acid has been gradually developed. Literature confirms that the intake of a certain amount of γ-aminobutyric could affect nervous system function including improvement of sleep quality, depression-like behavior, behavior and cognitive disorders. This paper is to provide reference for the application of γ-aminobutyric acid in medicine and functional food with the focus on GABA preparation, the relationship between γ-aminobutyric acid and intestinal flora, the effects of exogenous γ-aminobutyric acid on nervous system through intestinal flora and its preparation methods.