[Background] The brain-gut axis theory suggests that there is a potential link between intestinal flora and depression, but the current research is controversial, and the specific link is not yet determined. [Objective] To study the correlation between intestinal flora diversity and depressive symptoms in patients with first-episode depression, and to analyze the potential relationship between intestinal flora diversity and Desulfovibrio and depression, thereby providing theoretical support for subsequent longitudinal studies. [Methods] The V4-V5 region fragments in the 16S rRNA gene from the feces of the depression group (n=23) and the normal group (n=31) were genetically sequenced, and the Hamilton Depression Scale was used to evaluate the two groups. The α diversity test, β diversity test, t-test, Pearson correlation test, and Spearman correlation test were used for statistical analysis. [Results] There was no significant difference in the diversity of intestinal flora between the depression group and the control group (P>0.05). There were differences in the structure of intestinal flora between the two groups. The relative abundances of 28 genera and 40 species were significantly different at genus and species levels (P<0.05). There was a significant positive correlation between intestinal flora diversity (Shannon index and Chao1 index) and depressive symptoms (P<0.05). In the correlation test of the relative abundances and depressive symptoms at genus and species levels, Desulfovibrio was significantly correlated with depressive symptoms (P<0.05). [Conclusion] In this study, there are differences existed in the structure and composition of intestinal microbiota between patients with first-episode depression and healthy people. There is a significant correlation between intestinal flora diversity and depressive symptoms, and there is a significant positive correlation between the relative abundances of some flora such as Desulfovibrio and the depressive symptoms.