Type 2 diabetes mellitus (T2DM) has become a global public health problem. It has attracted much attention due to its increasing incidence rate and complex complications, and serious threats to human health and quality of life. Intestinal flora may be an important factor affecting the occurrence and development of T2DM in addition to genetics and life and diet styles. Its compositions may trigger T2DM by affecting the metabolism of short chain fatty acids and bile acids, endotoxemia and other ways. To reveal the correlation between intestinal flora and the pathogenesis of T2DM, it is suggested that the construction of intestinal flora homeostasis may become a new potential target for the prevention and improvement of T2DM.