Intestinal flora is an important component of the body and is closely related to the health of infants and toddlers.There are many hypotheses about the origin and establishment mechanism of intestinal flora, but most theories are still controversial.The intestinal flora is not static, and its biodiversity and abundance will continue to differentiate and evolve with the growth and development of nurslings.It is now believed that intestinal flora plays a variety of roles in maintaining the homeostasis of the infant's internal environment.This review summarizes the basic research on the physiology of infantile intestinal flora in recent years, to provide some reference for the development of this branch in the field of pediatrics.