The dentate line is an important component of the human digestive system and is located at the junction of the skin of the anal canal and the rectal mucosa. Above the dentate line is mucous membrane, which may become adenocarcinoma in case of cancer. The area below the dentate line has the appearance of skin tissue, and if it becomes cancerous, it will appear as squamous cell carcinoma, and the distribution of lymphatic and venous return is different between the upper and lower parts. Once there is an abnormal object near the dentate line, it should be considered that there is a possibility of disease, and it is best to treat it in time.