Small bowel cancer generally refers to malignant tumors of the small intestine. Among the malignant tumors, adenocarcinoma, carcinoid tumor, malignant lymphoma, smooth muscle sarcoma, etc. are most common. It can occur in all segments of the small intestine, and the age of onset is mostly below 50 years old, and is approximately equal for men and women. In terms of incidence of malignant tumors, the incidence of small intestine tumors is low, but the incidence of misdiagnosis and leakage is high because of the different clinical manifestations and pathological types, and the clinical examination methods are greatly restricted by objective conditions. Abdominal pain is the most common early symptom, which can be acute or recurrent, manifested as vague pain, distension or even severe colic. It can be accompanied by diarrhea, loss of appetite and other symptoms. Small bowel cancer lacks symptoms in the early stage, and only with the enlargement and rupture of tumor will there be symptoms of abdominal pain and obstructive digestive bleeding. Most of the GI bleeding is occult bleeding, which is manifested as positive stool occult blood test or black stool, and the patient may appear anemic; it may also appear intermittent small amount of bleeding, or even large amount of blood in stool. In malignant lymphoma or smooth muscle sarcoma, abdominal masses are also seen, which are wandering and intermittent. In addition, a small number of small intestinal cancers may develop into intestinal perforation at advanced stage, causing diffuse peritonitis.