ContextPolycystic ovary syndrome (PCOS), a common endocrine disorder in women of reproductive age, is closely associated with chronic low-grade inflammation and metabolic disturbances. In PCOS mice, dietary inulin has been demonstrated to regulate intestinal flora and inflammation. However, the efficacy of dietary inulin in clinical PCOS remains unclear.ObjectiveThe intestinal flora and related metabolic indexes of obese patients with polycystic ovary syndrome (PCOS) after 3 months of inulin treatment were analyzed.Setting and designTo analyze the intestinal flora and related metabolic indexes in healthy controls and obese patients with polycystic ovary syndrome after 3 months of inulin treatment.ResultsThe results showed that dietary inulin improved sex hormone disorders, reduced BMI and WHR levels in obese women with PCOS. In addition, the inulin intervention reduced plasma TNF-α, IL-1β, IL-6, and MCP-1levels. Inulin intervention increased the abundance of Actinobacteria, Fusobacteria, Lachnospira, and Bifidobacterium, as well as decreased the ratio of F/B and the abundance of proteobacteria, Sutterella, and Enterobacter. Correlation analyses showed a strong relationship among plasma inflammatory factors, sex steroid hormones, and the intestinal flora of patients.ConclusionsDietary inulin may improve obese PCOS women disease through the gut flora–inflammation–steroid hormone pathway.The clinical trial registration number: ChiCTR-IOR-17012281.