There is the largest micro ecological environment in the gut， which plays an important role in maintaining human health. Recent studies have shown that the diversity of gut microbiota plays an important role in the occurrence of depression and other mental diseases. However， the role of intestinal flora in the treatment of depression remains to be elucidated. At present， selective serotonin reuptake inhibitors （SSRIs） are commonly used as the first-line drugs in the treatment of depression. Many animal and clinical studies have shown that SSRIs can change the distribution of intestinal flora， and this change may be related to the mechanism of antidepressant effect of SSRIs. This article reviews the effects of SSRIs antidepressants on intestinal flora and its mechanism， to provide new ideas for clinical treatment.