Abstract: Intestinal flora is the microbiota located in the human intestines with a huge number and a wide variety, which has attracted extensive attention in the medical field because of its correlation to the pathogenesis of many human diseases. It has been demonstrated that the intestinal flora dysbiosis induced by the changes in the abundance and diversity is involved in the onset and development of diabetes. As one of the four types of diabetes mellitus, gestational diabetes mellitus (GDM) is a common complication during pregnancy, and the change of intestinal flora also plays an important role in the pathogenesis of GDM. Supplement of microecological modulator can improve the intestinal flora disorder, which provides new targets and new ideas for the prevention and treatment of GDM.