Human beings are "superorganisms" composed of 10% human cells and 90% microbial cells. There are about 10 14 and 1000 kinds of microorganisms living in human intestines, which are the largest and most complex biological communities of human beings and animals, mainly divided into physiological bacteria (Bacteroides, Bifidobacterium, Bacteroides, etc. ) with the host. Conditional pathogens (Enterobacteriaceae, Enterococcus, etc. ) and most pathogens (Proteus, Vibrio cholerae, Shigella dysenteriae, etc. ) mainly distributed in the colon. Under normal circumstances, intestinal flora maintains biological and antagonistic relationship, which affects human and animal health from digestion, nutrient absorption, energy supply, fat metabolism, immune regulation, drug metabolism, toxicity and other aspects. For the study of intestinal microecology, the traditional method is to obtain some information through selective culture or direct morphological observation of microorganisms, and then identify and classify them. The limitations of traditional culture methods are that the culture process is time-consuming and laborious, easily influenced by operation methods, and the sensitivity is low, so it is difficult or impossible to separate and cultivate most microorganisms in the existing technology; Culture technology can only detect culturable bacteria qualitatively, but can't identify unknown bacteria, and can't correctly reflect the quantity and diversity of intestinal microbial communities, which makes it impossible for human beings to fully understand the relationship between intestinal microorganisms and their hosts and hinders their understanding of intestinal microorganisms.