Generally, some bowel cancers can be detected by CT, but not all bowel cancers can be detected by CT, the most accurate way to diagnose bowel cancer is through colonoscopy. Due to the small size of early bowel cancer tumor, it is usually not easy to be detected through CT examination, while advanced bowel cancer, which is usually larger in size, may be accompanied by enlarged lymph nodes and metastasis, etc. CT examination can observe whether there is thickening and narrowing of intestinal tubes, as well as metastatic foci, and then indirectly diagnose bowel cancer. Abdominal CT can initially determine the possibility of intestinal tumor lesions, and for highly suspected tumors, it is necessary to further improve colonoscopy, barium enema X-ray examination and other methods to carry out auxiliary examination before confirming the diagnosis. Through colonoscopy, the site, size and shape of intestinal lesions can be observed visually, and biopsy can also be obtained under the direct vision of endoscopy for pathological examination, so as to make a clear diagnosis, and then according to the condition of the disease, the patient’s physical condition, etc., surgery, radiotherapy, chemotherapy, etc. can be adopted. Early detection, diagnosis and treatment of bowel cancer can improve the prognosis of the disease and prolong the survival period of patients.