The most accurate method to confirm the diagnosis of bowel cancer is fiberoptic colonoscopy. Besides, it can also be assisted by clinical manifestation, X-ray barium enema, rectal finger-pointing, fecal occult blood test and so on. Fiberoptic colonoscopy can directly observe the condition of intestinal mucosa and directly find out its existing lesions. If malignant lesions are suspected, biopsy is required for pathological examination, and pathological biopsy is the gold standard for confirming the diagnosis of intestinal cancer. Common clinical manifestations of intestinal cancer include changes in bowel habit and bowel symptoms, such as diarrhea, constipation, blood in stool or mucus-pus-blood stool, and sometimes abdominal mass, abdominal pain or even symptoms of intestinal obstruction. Patients with unexplained progressive weight loss should also be alerted to intestinal cancer. X-ray barium enema can show stiffness of intestinal wall, narrowing of intestinal lumen, weakening or disappearance of peristalsis, disorganization, destruction or disappearance of mucosal folds and filling defects in cancerous tumor. For those suspected of having rectal cancer, the easiest way is to perform rectal palpation, which can directly touch the lesions on the rectal wall. Fecal occult blood test is the most common method for colorectal cancer screening. If a patient has a positive fecal occult blood test, further gastroscopy and colonoscopy are needed.