The target population of screening includes all people with alarming symptoms of colorectal cancer such as blood in stool, black stool, anemia, weight loss and people aged 50-74 without alarming symptoms of colorectal cancer. Some related concepts combined with NCCN colorectal cancer screening guidelines and previous domestic colorectal cancer diagnosis and treatment consensus are summarized as follows: 1. High-risk group: Those who have any of the following are considered high-risk group: (1) positive fecal occult blood; (2) first-degree relatives with history of colorectal cancer; (3) previous history of intestinal adenoma; (4) personal history of cancer; (5) change in stool habit; (6) meeting any two of the following Any two of the following: chronic diarrhea, chronic constipation, mucus and blood stool, chronic appendicitis or history of appendectomy, chronic cholecystitis or history of cholecystectomy, long-term mental depression, and alarm signals. 2. General risk group: those who do not have any of the above.