To investigate the preventive effect and related machanism of 7,8-dihydroxyflavone (7,8-DHF) nanoparticles on metabolic syndrome (MetS), C57BL/6J female mice fed with two different dietary patterns (high-fat and low-fat) were intervened with 7,8-DHF nanoparticles (constructed using turnips polysaccharide as wall material) for 24 weeks. The dose of 7,8-DHF and its nanoparticles were all 10 mg/kg· body weight (BW) (based on the relative mass fraction of 7,8-DHF). At the end of the intervention, related MetS indexes, inflammatory factors and ovarian reserve function were determined by molecular biology techniques. It was shown that both 7,8-DHF and its nanoparticles could alleviate symptoms of MetS: significantly (P < 0.05) down-regulated the excessive body weight gain induced by high-fat diet (HFD) in mice, compared with the HFD control group, the body weights of mice in 7,8-DHF and 7,8-DHF nanoparticle groups decreased by 8.5% and 16.4%, respectively; obviously (P < 0.05) improved blood lipid, fasting blood glucose and insulin levels; markedly improved glucose tolerance and insulin sensitivity of mice; In addition, the 7,8-DHF nanoparticles constructed with turnips polysaccharide exhibited a better anti-MetS effect compared with 7,8-DHF alone. Furthermore, it was found that 7,8-DHF and its nanoparticles could significantly reduce the levels of circulating lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in serum. Moreover, 7,8-DHF and its nanoparticles can effectively protect the ovarian reserve function of mice, maintain the normal estrus cycle and the homeostasis of serum estradiol (E2) and follicular estrogen (FSH). Thus, it is speculated that the intervention effect of 7,8-DHF and its nanoparticles on MetS in female mice might attributed to its Protective effect on the ovarian reserve function by alleviating the systemic inflammation mediated by gut microbiota.