Abstract: Objective To investigate the effects of electroconvulsive therapy （ECT） on depressive behaviors and explore the mechanisms by which it regulates the composition and function of the gut microbiota via the microbiota-gut-brain axis.Methods A mouse model of depression was established using Chronic Unpredictable Mild Stress （CUMS）. The mice were divided into the control group, depression group and ECT group （n = 6 in each group）, and the depressive symptoms were assessed by behavioral experiments such as body weight change, open field test （OFT）, sucrose preference test, and forced swimming test （FST）. Meanwhile, histological and microcirculatory blood flow changes in the brain and intestines were assessed by HE staining, immunofluorescence （IF） and laser speckle contrast imaging （LSCI）. The levels of inflammatory factors such as TNF-α and IL-6 in intestinal tissues were detected by enzyme-linked immunosorbent assay （ELISA）, and changes in the diversity and abundance of gut microbiota in mice were analyzed by metagenomic sequencing. Results ECT significantly improved the behavioral performance of depressed mice, as reflected by weight gain, reduced immobility time in the FST and tail suspension test （TST） （all P < 0.05）. HE staining showed a significant reduction in intestinal inflammatory infiltration after ECT （P < 0.05）, and IF analysis demonstrated an increase in the expression of c-Fos in the hippocampal region （P < 0.05）. Inflammatory factor assay results showed that the TNF-α and IL-6 levels were significantly reduced in the ECT group （both P < 0.01）. In addition, the results of metagenomic sequencing showed that ECT significantly increased the diversity of gut microbiota, especially the abundance of Bacteroidota and Verrucomicrobiota was restored （both P < 0.05）. Conclusion ECT exerts antidepressant effects and improves sleep by regulating intestinal flora and improving gut-brain axis function.