Colorectal cancer is the general name of colon cancer and rectal cancer, which is a malignant tumor second only to stomach cancer and esophageal cancer among common cancers of the gastrointestinal tract, and with the improvement of our living standard, colorectal cancer has become one of the diseases with high incidence and mortality rate, and its incidence has been on a younger trend in recent years. The main factors causing colorectal cancer are the following three: 1. Diet structure: the main factor causing the development of colorectal cancer is the change of more and more people’s “meatless” eating habits, and the high-fat, high-calorie, low dietary fiber model has become the norm. Even many adults are afraid of malnutrition of their children and blindly worship the seemingly healthy concept of drinking milk and eating steak to grow taller abroad, and adopt the subjective behavior of “duck-filling”, resulting in a meat-based diet structure for many children since childhood, which eventually affects their whole life. The effect of diet on the incidence of colorectal cancer is also reflected in the ratio of men to women. The incidence of colorectal cancer is about 1.6:1 between men and women, with men being significantly higher than women. Compared with women, men are more likely to eat meat, fried, barbecued and alcoholic foods, and less likely to eat vegetables and fruits. Meat, deep-fried and barbecue are high-fat foods, which produce heterocyclic amino acids in the production process and carcinogens such as nitrite in the lumen of the colon, plus the reason of not loving to eat the fiber contained, thus reducing the amount of feces and the number of bowel movements, so that carcinogens exist in the body for a long time and the concentration increases more and more with the accumulation of time, thus providing a long-term formation of colon cancer “rich nutrition and environment”. While eating less meat, we also need to eat more fruits and vegetables. This is because fruits and vegetables are rich in fiber and have the ability to absorb water, they are small fighters to increase the amount of feces, just the opposite of meat, so they can neutralize the pressure brought to the stomach and intestines after eating meat and reduce the overly long stay of food in the body. But we need to remind you that we need to pay attention to the time and the amount of fruit we eat. We better not eat fruit when fasting, and do not eat fruit immediately after eating, and do not eat a lot of fruit after eating meat in order to neutralize the gastrointestinal pressure, these three cases not only easily lead to diarrhea, especially the last one because eat and go to eat, but will bring more pressure on the body, improve the quality of eating is the smart approach. Fruit consumption time is generally recommended in an hour after meals, this time the nutrients within the fruit is most easily absorbed, and will not cause pressure on the stomach and intestines. Therefore, meat and vegetables, “vegetables are the main character, meat as a supporting role”, appropriate to eat meat, choose the most suitable for their own, after eating without any burden and discomfort eating habits is good. Genetic factors: Genetic factors account for about 10% of the occurrence of colorectal cancer. If there is a family history of bowel cancer, the chance of having this disease in his life is about 8 times higher than that of ordinary people. However, it is not true that everyone with such a condition will get colon cancer, we don’t need to be anxious about it, emotional influence also plays a role in the occurrence of the disease, so relax and face it normally, we just need to do regular medical checkups. It is generally recommended that people who are around 40 years old and have never had gastroscopy before should go to a regular hospital for colonoscopy and, if necessary, increase the number of tumor marker tests of the digestive system if they suddenly have abnormal stools (constipation or diarrhea), abdominal pain before stool, or blood in stool. Early prevention, early detection and early intervention” is the gold standard to prevent the occurrence of cancer. 3, colorectal polyps (adenomatous polyps), chronic inflammation: colorectal adenoma is an important reminder of precancerous lesions of colorectal cancer, generally speaking, the larger the tumor, the more irregular the morphology, the higher the villi content, the heavier the epithelial heteromorphic hyperplasia, the greater the chance of relative cancer, so patients with multiple intestinal polyps should pay more attention. Then again, if the pathology is poorly typed, it must be reviewed regularly. Chronic non-specific ulcerative colitis, due to its chronic inflammatory long-term stimulation, is about six times more likely to occur in patients with primary sclerosing cholangitis if it is also combined with colorectal cancer than in normal people. In addition, chronic inflammation such as chronic amoebic enteropathy and chronic bacterial dysentery can become cancerous through granulomas, inflammation or pseudopolyps. In addition to the above-mentioned factors, radiation damage is also one of the factors causing the occurrence of colorectal cancer. It has been documented that the incidence of colon cancer in women after local radiation therapy for cervical cancer is significantly higher than that of the normal population. Meanwhile, primary and acquired immunodeficiency may also be related to the occurrence of colorectal cancer. Therefore, we can prevent the occurrence of colorectal cancer from daily lifestyle, understanding family medical history and regular medical checkups and tests.