Low rectal cancer refers to rectal cancer that occurs below 8cm from the anal verge, including ultra-low rectal cancer. 3cm low rectal cancer belongs to ultra-low rectal cancer, whether it is serious or not needs to be decided according to the stage of the cancer, the specific condition and the patient’s physical condition, and cannot be generalized. Patients with 3cm low rectal cancer may have symptoms of rectal irritation, such as bleeding in stool, change of stool character, urgency and heaviness, and feeling of incomplete bowel movement, etc. Doctors will choose appropriate surgical methods according to patients’ individual conditions. For early stage 3cm low rectal cancer, local excision can be taken, generally the prognosis is relatively good and the symptoms can be relieved to some extent. In case of middle stage 3cm rectal cancer, anal preservation surgery can be carried out. If the tumor is large and the patient has strong willingness to preserve the anus, chemotherapy and radiotherapy are needed first, and then anal preservation treatment can be taken after the tumor shrinks. However, for advanced 3cm rectal cancer, which is poorly differentiated, permanent colostomy is needed in the abdomen, supplemented by chemotherapy and radiotherapy if necessary. The treatment of advanced rectal cancer, which is usually more serious, focuses on prolonging the patient’s life and improving the quality of survival. Early detection, early diagnosis and early treatment of low rectal cancer can effectively improve the prognosis of the disease and reduce the adverse effects of the disease. It is recommended that patients actively and promptly undergo regular treatment.