Bowel cancer is generally divided into colorectal cancer and small intestine malignancies, which are common malignant tumors of the digestive system. Its incidence has certain geographical characteristics and is closely related to lifestyle. The main clinical manifestations of colon cancer are abdominal pain, blood in stool, changes in bowel habits and traits, abdominal masses, intestinal obstruction and systemic symptoms (such as anemia, emaciation, weakness and low fever, etc.). The clinical manifestations are related to the size, location and pathological type of lesions. Patients with early stage colon cancer can be clinically asymptomatic, and some signs and symptoms appear gradually as the disease progresses. Early rectal cancer is limited to the mucosal layer and often has no obvious symptoms, only intermittent small amount of blood in stool and change in stool habit. After the tumor progresses, it may break down and become infected, which may cause rectal irritation symptoms, such as increased frequency of stool, urgency and heaviness or incomplete defecation. After tumor rupture and infection, there may be bleeding and mucus discharge. Blood in stool is the most common symptom of rectal cancer, and more than 80% of rectal cancers have blood in stool. The clinical manifestation of small intestine malignant tumor is very atypical, often showing one or more of the following symptoms: abdominal pain is the most common symptom, which can be vague, distending or even severe colic; intestinal bleeding, which can be intermittent tarry stools or bloody stools, or heavy bleeding; intestinal obstruction, most of which is chronic and recurrent; intra-abdominal mass, which is usually in an irregular position; intestinal perforation, which can lead to peritonitis in acute perforation and intestinal fistula in chronic.