Colorectal cancer is a common malignancy of the digestive tract, and the gut microbiota is closely related to the occurrence and development of colorectal cancer. The intestinal florae mainly change the host intestinal immune environment and affect the function of the intes-tinal barrier by releasing toxins and producing metabolites to participate the occurrence and deve-lopment of colon cancer. The intestinal florae can be used as biomarkers for early screening and prognosis prediction for colorectal cancer. In addition, the intestinal florae can affect the efficacy of chemotherapy, radiotherapy and immunotherapy for colorectal cancer. The authors review the research progress of gut microbiota in occurrence and development, screening, prognosis prediction and treatment of colorectal cancer, and discuss the application prospects of gut microbiota in the prevention and treatment of colorectal cancer.