Abstract: Objective: To investigate the effects of normal group without gavage of LBP and various doses of Lycium barbarum leaves polysaccharides (LBP) on mouse metabolism, antioxidant, immune function, and intestinal microorganisms, C57BL/6 female mice were continuously gavaged with 50, 100, and 150 mg/kg of LBP for 7 weeks. Methods: The ultrastructure of the intestinal mucosa of each group of mice was observed by scanning electron microscopy, and the levels of serum malondialdehyde (MDA), activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) were detected to evaluate the antioxidant capacity of different doses of LBP, the number of T, B and dendritic cells (DC) in the spleen was detected by flow cytometry, fully automated biochemical analyzer for the detection of biochemical indicators in mouse serum, and the changes of intestinal flora in mouse fecal samples were detected by 16S RNA sequencing. Results: There were no variations in the intestinal mucosa's ultrastructure between the groups. The activity of T-SOD (45.27±2.73 U/g) and GSH-Px (1585.76±33.69 U/g) was increased by high-dose LBP, while MDA levels (6.15±1.03 nmol/g) were decreased. The high dose group of LBP could significantly boost the number of T and DC cells, lower serum levels of aspartate aminotransferase (161.48±14.98 U/L) and triglycerides (0.30±0.04 mmol/L) and can increase the relative abundance of probiotic genera like Dubosiella, Akkermansia, and Lactobacillus, and others in the gut. Conclusions: The findings of this study demonstrated that LBP given orally to mice had no effect on the structure of the intestinal mucosa, while also improving antioxidant capacity, enhancing immune system function, enhancing intestinal microflora, and promoting triglyceride and aspartate aminotransferase biological metabolism in mice. This will provide the theoretical basis for the development and utilization of LBP in food, medicine and health products.