Abstract: The gut microbiota and its metabolites have shown significant value in the diagnosis and treatment of depression. This paper summarizes the changes in gut microbiota and metabolites in patients with depression at different stages, and explores their feasibility as early diagnostic biomarkers and the basis for personalized treatment. Meanwhile, the article analyzes various interventions that regulate the gut microbiota and their impact on depressive symptoms. The paper also discusses gut microbiota-based therapeutic strategies and suggests the need for enhanced multimodal combined interventions and the development of precision medicine to improve the effectiveness of depression diagnosis and treatment.