Ulcerative colitis (UC) is a type of chronic inflammatory recurrent disease. At present, the etiology and pathogenesis are still unclear, and immune factors are usually considered to be the final link in the pathogenesis of UC. Due to the increasing incidence of this disease, longer course of disease, and difficult to heal, related research has gradually deepened, and related researches on intestinal flora, immunity, genetics, etc. have become hotspots. A large amount of evidence indicates that regulatory T cells (Treg), helper T cell 17 (Th17), Th17/Treg immune axis and intestinal microbiota in UC patients play an important role in regulating the occurrence and development of diseases. In recent years, the intestine has been gradually discovered There is also a certain correlation between the tract microbiota and the Th17/Treg immune axis. Therefore, this article examines a large number of relevant Chinese and English materials at home and abroad in recent years to analyze the Th17/Treg cells, intestinal microbiota and the relationship between the two in UC patients. The existing relevance and other issues are briefly discussed and summarized in order to provide more practical basis for clinical targeted therapy.