With the advancement of medical technology, the wide use of anastomosis, and the popularization of double anastomosis technology, more patients with low rectal cancer have their anus preserved. The weight of the physician’s artificial technical factors has declined. To put it in plain words: there is almost no such problem in professional surgeons that Physician A’s high level can preserve your anus, while Physician B’s low level can’t preserve your anus. This is the psychological misunderstanding of many patients. The following are some factors affecting anal preservation in rectal cancer: the first one is the distance, that is, the distance of the lesion from the anus. The resection of tumor is not only to remove the lesion itself, but also to remove part of normal intestinal tube next to the tumor. We call it “safe distance”. We all understand that if the tumor is very close to the anus, without this safe distance, the gods can not protect the anus. In fact, the most disturbing thing for physicians and patients is the kind of rectal cancer that is not up and down, not far but not close. It is a pity that the anus is not protected, while the anus is protected and there is a great risk of recurrence. Some patients through the physician and the patient’s joint efforts to preserve the anus, achieved good results, patients and families are happy. And there are also some patients who have localized recurrence soon after low anal preservation surgery, not only need to operate again, but also the anus is not preserved. Both the patients themselves and their families regretted the decision to strongly request anal preservation at that time. The second is space. The surgical operation of rectal cancer (especially the lower position rectal cancer) is operated in the small pelvic cavity. The size of this space has a great impact on the ability to preserve the anus. Generally female, tall and thin patients have more space, which is favorable for anal preservation operation. Male, small, obese patients have less space, which affects anal preservation. Often patients due to narrow pelvic space (physiological or pathological), even the bowel closure instruments can not be put in, naturally affecting the success rate of anal preservation. The third is the surrounding conditions. Some patients have larger tumors, deeper infiltration, close relationship with peripheral organs and obstruction, and so on. The risk of local recurrence is higher, in order to control the risk of recurrence as well as facilitate the follow-up treatment. Doctors will also advise patients to carefully choose whether to preserve the anus or not. To be honest, the question of whether or not to preserve the anus can’t really be explained in a few words or paragraphs. There are many more factors to consider. The job of the specialist is to conduct a comprehensive assessment of the patient without violating the principles of treatment, to formulate a treatment plan that is in the best interest of the patient, and to carry out the treatment after obtaining the approval of the patient and his/her family.