Gastroesophageal reflux disease (GERD) is a global digestive system disease caused by the reflux of gastric contents into the esophagus and the injury of esophageal mucosa. At present, the pathogenesis of GERD is not completely clear. Studies have found that GERD is closely related to intestinal flora disorder and small intestine bacterial overgrowth (SIBO). Changes in intestinal flora can participate in the occurrence and development of GERD by activating immune and inflammatory reactions, affecting gastroesophageal motility and other mechanisms. In addition, intestinal flora can also indirectly regulate and affect the pathogenesis of GERD by causing some metabolic diseases. This paper aims to review the relationship between GERD and intestinal flora.