Whether the anus can be preserved or not is related to the quality of life after surgery, so rectal cancer patients and their families are very concerned about this issue. 1.Related to the location of rectal cancer. Rectum is generally divided into upper, middle and lower segments, 5-7 cm from the anal verge is the lower segment, 7-11 cm is the middle segment and 11 cm or more is the upper segment. At present, most cancers in the middle and upper rectum are performed anus-preserving surgery, while cancers in the lower rectum within 5 cm from the anal verge generally cannot preserve the anus. In recent years, with the application of anastomosis and improvement of surgical methods, some people also try to adopt anus-preserving surgery for certain cancers of the lower rectal segment that are 5-7 cm from the anal verge without affecting the principle of complete removal of the tumor. 2.Related to the infiltration and metastasis of rectal cancer to the tissues and organs around the intestinal wall. If there is serious infiltration, metastasis and fixation, generally anal preservation surgery is not performed to avoid residual cancer cells due to incomplete resection and recurrence of anastomotic cancer, which affects the survival rate. 3.It is also related to the width of the pelvic cavity and the fatness of the patient’s body. It is relatively difficult for those with deep and narrow pelvis and thin shape to preserve anus, while it is relatively easy for those with shallow and wide pelvis to preserve anus. In addition, there are more complications such as anastomotic fistula after reluctant anus preservation, and the risk of anus preservation surgery in elderly people is greater than that of non-anus preservation surgery, and the mortality rate is also higher, which are also important factors to decide whether to preserve anus.