Colorectal cancer (CRC) is a common malignant tumor of the gastrointestinal system, and its incidence is increasing year by year with the change of lifestyle. The main causes of colorectal cancer are: first, double high diet (high protein, high fat) and low fiber diet; second, obesity; third, genetic factors. In addition, there are also pathogenic factors such as smoking and environmental pollution. Dysbiosis of intestinal flora is closely related to intestinal cancer Recent studies have found that dysbiosis of intestinal bacteria also increases people’s risk of developing colorectal cancer. The intestinal tract is the largest micro-ecosystem in the human body, with hundreds of millions of bacteria gathered in the human body community, of which more than 90% live in the intestinal tract, known as the “intestinal flora”, also known as “intestinal microorganisms”, and intestinal microbial homeostasis is important for digestion, nutrient metabolism, and human development. Gut microbial homeostasis plays an extremely important role in digestion, nutrient metabolism, human development, immunity and disease production. It is estimated that the total weight of bacteria in the gut of a normal adult can be 1-1.5 kg, and the number of bacteria can reach 10 to the 14th power. The large number of bacteria does not cause harm to the human body, rather, the intestinal microflora structure to maintain a relative balance, the interaction of beneficial and harmful bacteria to better ensure intestinal health. It is found that intestinal flora testing is an important part of the multidimensional detection system of intestinal cancer, and by improving the dysbiosis of intestinal flora can reduce the incidence of colon cancer and inhibit the growth and deterioration of colon cancer. As we know, the gastrointestinal tract of healthy people is inhabited by a wide variety of microorganisms, which are mainly divided into beneficial bacteria, harmful bacteria and neutral bacteria, and only when these flora are in balance, the intestinal tract will be healthy. However, when the human body is affected by various factors such as the outside world, the intestinal flora will easily become dysbiosis and the human body will suffer from diarrhea and other intestinal diseases.