Abstract: Recently, the incidence of colorectal cancer in China has increased yearly, and it has become one of the most common malignant tumors of the digestive tract. With in-depth molecular biology and metagenomics studies, it has been found that changes in the intestinal microflora and its metabolic patterns can be achieved by destroying normal tissue cell DNA, activating oncogenic signaling pathways and producing tumor-promoting metabolites and inhibitory antibodies. Multiple factors such as the tumor immune response affect the occurrence and development of colorectal cancer. Therefore, attempts have been made to treat and prevent tumors using microecological agents. Through research, it is found that microecological preparations represented by probiotics and excreta transplantation technology can regulate intestinal microflora, induce apoptosis and cell cycle arrest of colorectal cancer cells, secrete anti-tumor cytokines, and regulate the immune system to resist tumors. Microecological preparations have brought hope to patients with colorectal cancer, but the specific mechanism of action of intestinal microflora in colorectal cancer is still unclear, and further large-scale studies are needed. This article reviews the research progress of intestinal microflora and colorectal cancer in order to explore a new method for the diagnosis and treatment of colorectal cancer.