Colorectal cancer is known as the “silent” disease because many patients have no symptoms in its early stages. In fact, the cure rate after the onset of symptoms is only about 50%, while in the early stages, the chance of cure is 80% or higher. The role of screening is to detect cancers that have no clinical manifestations or diseases that may develop into cancer. Since September 2009, the Department of Anorectal Medicine of Nanjing Chinese Medicine Hospital has been conducting free colorectal tumor screening, which has been well received in the society. There are three main categories of people who come for screening: 1) those with long-term irregular stools, mucus in the stool and abdominal pain; 2) those who have a history of “blood in stool” and have been treated as hemorrhoid disease, but have not undergone colonoscopy as recommended by doctors, but are not sure; 3) those who come for screening without any symptoms. As of December 18, a total of 1,613 people participated in the screening process, and the results showed that 293 patients had positive occult blood tests, 145 of whom underwent colonoscopy at our hospital, and 66 were found to have abnormalities: 20 cases of inflammatory colorectal disease, 368 cases of polyps, 6 cases of colorectal cancer, and 2 cases of colorectal melanosis. All 66 patients with abnormal manifestations received timely treatment, especially 36 patients with colorectal polyps. Although most polyps are benign, most colon cancers evolve from polyps, and when polyps are removed in time, cancer is prevented. In the process of screening, the main reasons for people with positive occult blood test but no further colonoscopy are: 1) fear of colonoscopy; 2) thinking that they are not a big deal and “looking for trouble”. In fact, colonoscopy is an effective method to prevent intestinal cancer, because colonoscopy can not only detect intestinal cancer, but also conduct a complete examination of the whole intestinal tract to discover intestinal diseases, and if polyps exist, they can be removed in time if conditions permit. A retrospective analysis of 66 patients with abnormalities found during screening revealed that most of these patients had a “high-fat, low-fiber” diet, excessive energy intake, excessive alcohol consumption, and reduced physical activity. High-fat diet increases the activity of 7a-dehydroxylase, leading to increased formation of secondary bile acids, while fiber has the opposite effect and reduces the concentration of deoxycholic acid in the intestine by inhibiting reabsorption, dilution, adsorption and chelation, increasing the solid phase material in the stool and promoting excretion; fiber also has the effect of changing intestinal flora, affecting the structure and function of intestinal mucosa, and influencing the growth rate of mucosal epithelial cells. It also affects the growth rate of mucosal epithelial cells, regulates intestinal pH, and strengthens the mucosal barrier through mucin to reduce the intestinal toxic substances on the intestinal epithelium. In addition, it is also found that such patients generally do not like to drink “tea”, in fact, tea polyphenols are a strong antioxidant, which can inhibit the carcinogenic effect of cancer-inducing agents. The most common symptoms of colorectal cancer are bleeding during bowel movements (blood in stool, blood dripping after stool, or blood on toilet paper); changes in bowel habits, such as new constipation or persistent diarrhea; abdominal pain and unexplained weight loss may be signs of cancer progression. High-risk factors include a history of breast, uterine, or ovarian cancer, inflammatory bowel disease (ulcerative or clonal colitis), and a family history of colorectal polyps or cancer. For those who have alarm symptoms, they should be promptly seen in the hospital; for those who are at high risk, surveillance should be enhanced.