To study whether mood stabilizers improve symptoms in bipolar disorder (BD) patients by affecting gut microbiota. Methods: The Young Manic Rating Scale (YMRS) was used to evaluate the clinical symptoms of 42 patients with BD before and after treatment, and patients’stool samples were collected for DNA extraction. After PCR amplification, library construction, and quality control, OTUs were obtained by 16S rDNA high-throughput sequencing and Uparse software clustering screening. QIIME software was used to calculate the index of α diversity, including the Chao1 index, observed species index, Shannon index, and Simpson index. PCoA analysis using Bray-Curtis distances based on OTUs was performed to calculate β diversity. LEfSe software was used to screen for different species by linear discriminant analysis (LDA). Serum IL-1 β and TNF-α levels were detected by ELISA before and after treatment in BD patients. Results: The indexes of Chao1, observed species, Shannon and Simpson in the BD group were lower than those in the healthy control (HC) group (P<0.05). The indexes of Chao1 and observed species in the BD group were higher after treatment than before (P<0.05). The abundance of Firmicutes and their subordinate Clostridiales, Clostridia, Ruminococcaceae, and Veillonellaceae, Proteobacteria, and Actinobacteria in the BD group before treatment was higher than that in the HC group, while the abundance of Firmicutes and its subordinate Lachnospiraceae, Acetobacteraceae, and Bacteroidales in the BD group was higher after treatment than before (P<0.05). The relative abundance of Lachnospiraceae in the BD group before treatment was lower than that of the HC group and the BD group after treatment (P<0.05), but there was no significant difference in the relative abundance of Lachnospiraceae between the BD group after treatment and the HC group (P>0.05). The relative abundance of Lachnospiraceae was negatively correlated with YMRS score and with levels of IL-1β and TNF-α (P<0.05). Conclusion: Mood stabilizers can relieve symptoms of bipolar disorder by way of gut microbiota changes.