The conditions of anal preservation for low rectal cancer are as follows: firstly, it depends on the location of the tumor, the higher the location of the tumor, the more chance of anal preservation, the lower the tumor, the less chance of anal preservation; secondly, it depends on the biological characteristics of the tumor, such as the extent of tumor infiltration, the size and malignancy of the tumor. If the tumor invades the anal levator and anal sphincter, the patient will lose the condition of anal preservation; thirdly, it depends on the surgeon’s surgical skill and ability, for the same tumor, some surgeons may be able to perform anal preservation while others may not; fourthly, it depends on the state of anal function of the tumor. If the patient is older and the function of the anus itself is not very good, the function of the anus may be worse after the anal preservation surgery.