Abstract: In recent years， with the deepening of the research on the regulation of intestinal flora， the "brain-gut" axis， which is used to describe the complex network relationship between gastrointestinal microflora and their hosts. It is a bidirectional information regulation pathway based on the presence of intestinal flora in mammals and plays an important role in human health and disease process. Depression is a long and recurring chronic mental illness that differs from simple mood disorders. Studies have shown that intestinal flora can significantly influence host stress response， anxiety， depression and cognitive function through the brain-gut axis. Based on the intestinal flora， this paper reviewed the research status and mechanism of depression， aiming to provide basis and reference for the treatment of depression.