In this study, tea protein lipid-lowering peptides were prepared by enzymatic hydrolysis, and 3T3-L1 preadipocytes and high-fat mice were used to investigate its in vitro and in vivo lipid regulating effect. The results showed that tea protein lipid-lowering peptides could significantly inhibit the adipogenic differentiation of 3T3-L1 preadipocytes and reduce lipid accumulation. At the peptides concentration of 0.1 mg/mL, the content of total triglyceride, total cholesterol, low-density lipoprotein, and high-density lipoprotein of the cells decreased or increased by 38.57%, 47.71%, 46.68%, and 49.29%, respectively. Feeding lipid-lowering peptides could significantly inhibit the weight gain of high-fat mice, reduce fat accumulation and organ burden, and inhibit the degeneration of liver and epididymal fat. High concentration of lipid-lowering peptides (200 mg/kg) significantly reduced the atherosclerosis index and coronary artery risk index by 58.52% and 42.90%, respectively. Intestinal flora analysis showed that lipid-lowering peptides could increase the ratio of Firmicutes to Bacteroidetes, and increase the relative abundance of Muribaculaceae, while decreasing the overall abundance of Bacteroidetes. These changes help to restore the homeostasis of intestinal flora and thus have a positive regulatory effect on obesity and related metabolic disorders.