Rectal cancer can be examined by rectal fingerprinting, laboratory examination, endoscopy and imaging examination. 1. Rectal diagnosis: Rectal diagnosis is a more important physical examination for diagnosing low rectal cancer, which can understand the size, orientation, shape and blood staining of the mass. 2. Laboratory examination: fecal occult blood test can be used as the initial screening method for rectal cancer, as well as tumor marker test, such as carcinoembryonic antigen. 3. Endoscopic examination: such as anoscopy, colonoscopy, etc. Anoscopy can be used as routine examination in outpatient clinic, and colonoscopy can observe the whole large intestine from anus to ileum and take biopsy for histopathological examination. 4. Imaging examination: magnetic resonance imaging examination can assess the depth of tumor infiltration in the intestinal wall and whether the lymph nodes have metastasized, etc. Intrarectal ultrasonography can understand the depth of tumor infiltration. Rectal cancer patients need to go to the hospital in time, follow the doctor’s instruction for examination and treatment, and avoid self-medication.