According to statistical analysis, the incidence of colorectal cancer is increasing year by year, and it has shown the characteristics of youthfulness, urbanization and tendency of family gathering. With the improvement of people’s living standard and westernization of lifestyle, the incidence of colorectal cancer is bound to increase in China due to the increase of low-fiber, high-fat and high-protein diet. Therefore, if you have symptoms such as blood in stool, purulent stool, mucus stool, chronic diarrhea, unexplained abdominal pain, thin stool, stubborn constipation, change in stool character, urgency and heaviness, as well as family history, we suggest you to have a colonoscopy to detect precancerous lesions, colorectal adenoma and early colorectal tumor in time, which can be cured by resection under colonoscopy to avoid the progress of disease.