Abstract: Human Milk Oligosaccharides (HMO)is a sort of natural oligosaccharides existing in human milk.They not only have protective functions against intestinal infections but also play an important role in keeping gastrointestinal ecosystem balance. In addition,they also have many other important biological functions under investigation.In the struggle of human being against pathological microorganisms,HMO offers us a new concept and a valuable choice.

Key words: Oligosaccharide , Biological function