The intestinal tract is not only an important place for digestion and absorption of the human body, but also the largest immune organ, which plays an important role in maintaining normal immune defense and other functions of the body. The survival and reproduction of intestinal microorganisms depends on the special micro-ecological environment in the intestinal tract, and they can also complete a variety of metabolic functions that the human body does not possess. Intestinal microorganisms have a great influence on the occurrence and development of human diseases, in which the bacteria in the intestinal tract constitutes the largest proportion with a number more than 100 trillion, directly or indirectly participates in the processes of immune regulation, substance metabolism, digestion and absorption in the human body, and plays an important role in the protection of intestinal mucosa, the maintenance of intestinal homeostasis and the normal function of the body, as well as disease resistance. The microflora colonized in the intestinal tract are closely related, are always relatively independent but interrelated, and their populations and numbers maintain a dynamic balance. Treatments such as surgery, radiotherapy, chemotherapy and fasting, mechanical intestinal preparation or the use of antibiotics can change its composition and function, thus affecting the dynamic balance of gut microbiota, and even lead to flora imbalance. Studies have found that gut microbiota imbalance can directly or indirectly affect the occurrence and development of colorectal cancer through immunomodulatory and inflammatory reactions, genotoxic reactions, metabolites and so on. In recent years, the role of gut microbiota in non-invasive diagnosis, radiotherapy, chemotherapy and immunotherapy of colorectal cancer has been gradually confirmed. In addition, the intake of probiotics and other microbial products through diet regulation and fecal therapy also provide a new idea for the prevention and treatment of colorectal cancer and the related complications. A comprehensive understanding of the relationship between gut microbiota and colorectal cancer can provide a theoretical basis for the biological prevention and treatment of colorectal tumors. Based on the above background, the authors address the relationship between gut microbiota and colorectal neoplasm through reviewing the relevant literature in recent years.