Nowadays, the wide application of colonoscopy in clinical practice is important for the diagnosis of diseases, especially for gastrointestinal bleeding, constipation, acute abdominal pain and other conditions, which can understand the lesions of the intestine, but colonoscopy does have higher risks compared with other imaging examinations, which can also bring uncomfortable reactions to patients: 1. Advantages: If patients have unexplained blood in stool, change in stool habit, abdominal pain, abdominal mass, wasting anemia and other signs or suspected of having lesions in the colon, rectum and terminal ileum, the diagnosis cannot be clearly made by CT or MRI, the diagnosis can usually be clearly made by colonoscopy, and if tumor invasion is suspected, pathological tissue can also be directly removed for tissue biopsy. Patients with lesions such as stenosis, ulcers, polyps, carcinomas, diverticula, etc. in the colon suggested by barium enema and need further confirmation can be further diagnosed by colonoscopy. Colonoscopy can also perform microscopic hemostasis, polypectomy, rectification of intussusception and intestinal torsion, and dilatation of intestinal strictures, which is less invasive than open surgery. The clinical can also be painless colonoscopy, the patient pain is less. 2, disadvantages: first of all, there are certain limitations of colonoscopy, not all people can be colonoscopy, so before the examination need to explain clearly with the doctor’s medical history, to exclude contraindications, such as anal, rectal severe stenosis, acute severe colitis patients, women during pregnancy and other groups are not suitable for colonoscopy. Some people are sensitive and may experience discomfort or pain, which can usually be relieved soon. Colonoscopy may also cause complications such as intestinal perforation, intestinal bleeding, mesenteric laceration, and cardiovascular accidents. However, with the development of medical technology nowadays, complications can be effectively avoided by performing colonoscopy in regular hospitals.