Nowadays, the main clinical examination of the colon is performed by e-colonoscopy. The e-colonoscope has a fiber mirror that can be bent inside the intestine, and the mirror is inserted through the anus, passing through the rectum, sigmoid colon, descending colon, transverse colon and then ascending colon, and arriving at the ileocecal cecum, completing the examination of the entire large intestine. It is necessary to take oral laxatives in the morning of the day before the procedure to excrete all the stool from the intestine and keep the intestinal cavity clean, so that the condition of the intestine can be clearly examined. Many colorectal tumors, inflammation of the colon and other conditions of the colon are examined by e-colon, so the basic examination of the colon is done by e-colonoscopy.