The incidence of colorectal cancer (CRC) is closely related to dietary factors. Dietary factors greatly affect the structure and function of intestinal microorganisms. In the process of cholesterol bile acid metabolism, the gut microbes participate in the conversion of primary bile acid to secondary bile acid and play an important role in the occurrence and development of CRC. Erchen decoction (ECD) has been widely used in basic research and clinical treatment as a traditional Chinese medical prescription, particularly for patients who are overweight and exhibit dyslipidemia. It is widely used in clinical practice in patients with phlegm syndrome in early colorectal cancer. However, the effects of this treatment on microorganisms and the underlying metabolic mechanisms are still unclear. In this study, a model of high-fat diet and azoxymethane combined with dextran sodium sulfate (AOM/DSS) was established, and ECD intervention was administered to investigate the incidence rate of CRC under different dietary conditions, as well as the effect of ECD intervention on CRC mice fed a high-fat diet. The results showed that the incidence rate of colorectal neoplasms increased under conditions of a high-fat diet, and ECD could reduce the incidence of CRC by regulating abnormal lipid metabolism and improving the structure and function of the intestinal flora.