At present, colon cancer in China is gradually getting younger, and the methods of colon cancer screening are as follows: 1. In the past, colonoscopy was required for patients older than 50 years old, but now it is recommended that patients over 40 years old with bloody stools must undergo colonoscopy, and those with positive stool occult blood test for three consecutive days must undergo colonoscopy, which are means of early detection of colon cancer; 2. If there is positive tumor factor in the stool, colonoscopy can be done directly, and it is possible to find tumor, and the stool examination is not harmful to the body and more convenient; 3.Patients with family history, if the patient’s family members or elders have had colon cancer or intestinal polyps or long-term constipation, these are high-risk factors for tumor, and they must perform colonoscopy; 4.A year after polypectomy, colonoscopy should be repeated once.