In recent years, there have been more and more articles illustrating the connection between gut microbiota and diseases, such as inflammation, cancer, neurodegenerative disease, obesity and depression. However, over 70% of these microorganisms cannot be isolated with traditional methods from of their hosts, which limits people's understanding on them. Thanks to the development of metagenomics sequencing, researchers are able to study the microbial darkmatter in the digestive tracts of humans. The culture of intestinal organoids makes it convenient for scientists to imitate the environment in human body so as to show the more complex ecological mechanism. Because of these advanced technologies, studies on gut microbiota appear one after. Researchers hope to provide important theoretical foundation on the association between gut microbiota and diseases as well as the regulation of human health by studying the species of these organisms and their relationship with humans.