In the past, for cancer patients, “curing cancer and saving life” was the only goal, because it was not easy to survive, and it was impossible to have other wishes, to achieve this goal, surgeons kept exploring how to expand the scope of resection for complete clearance, for fear of missing the cancer cells that had spread, leading to recurrence and metastasis after surgery, however However, decades of efforts have not been rewarded, and the 5-year survival rate after surgery has not improved significantly. With the progress of society and the improvement of living standard, tumor patients have higher and higher demands on the quality of life, pursuing the dual goal of “survival and quality of life”. After nearly 20 years of efforts, 70%-80% of patients with low rectal cancer have preserved their anus and avoided permanent abdominal colostomy, and the benefits of this change are obvious. Second, the establishment and improvement of the theoretical basis of anal preservation surgery 1. The traditional direction about the three lymphatic drainage of rectum is wrong. In the upper and middle rectum, there is only upward lymphatic drainage in the rectum above the peritoneal reflex, and there is no lateral or downward drainage; the main lymphatic drainage direction in the rectum below the peritoneal reflex is still upward, but there is lateral drainage; only the anal canal part has lymphatic drainage in three directions. 2, foreign scholars proposed that the rectum is lying on the curved sacral recess, and once it is fully free, there can be 3-5Cm extension. This finding requires that the surgeon should decide the position of the tumor only after sufficient freeing of the rectum, and then decide whether the anus is preserved. 3. The study found that retrograde spread of tumor in the intestinal wall is rare generally within 2cm, rarely greater than 2cm, and even if it occurs, it appears to be a more advanced and malignant lesion. The conclusion from this study is that resection of normal rectum distal to the tumor is not less than 2 cm is sufficient, and this is also the principle generally accepted and implemented internationally. A lot of clinical data prove that the length of distal resection is not related to recurrence and prognosis. 4. The application of rectal tubular anastomoses and closures has, to some extent, solved the operational difficulties of performing rectal anastomoses in the deep pelvic cavity and ensuring the safety of the anastomosis. The introduction of double anastomosis has greatly promoted and facilitated butt-end anastomosis in the deep pelvic cavity and significantly improved the success rate of anal preservation surgery. Third, sexual function and urinary function have become another goal to pursue to improve the quality of life. In the past, the first thing a person thought of after getting cancer was how to destroy the cancer to save his life. For a rectal cancer patient, the anus had to be sacrificed in order to destroy the cancer, and most of them still accepted it. But now when anal preservation surgery can be successfully performed in about 2/3 of the cases of low rectal cancer, people gradually become more resistant to sacrificing the anus and make a strong demand for preserving the anus. The inconvenience and emotional trauma of a permanent abdominal colostomy is undoubtedly obvious. However, is it possible to say that the patient can live a normal life with a preserved anus? The truth is that there are still some patients who have hidden problems that they are too ashamed to talk about or don’t want to talk about. What is that problem? It is sexual dysfunction! Traditionally, the incidence of sexual dysfunction after radical resection of rectal cancer is as high as 25%-75%, only if the physician does not ask the patient, and in the past, very few patients took the initiative to reflect this problem to the physician, so many surgeons know very little about it, and even if the patient raises this issue, some surgeons feel that in order to completely remove the tumor, injury to the pelvic vegetative nerve is an unavoidable result. In fact, with the development of expanded lateral lymphatic dissection and autonomic nerve preservation, the effect of preserving the autonomic nerve on urinary and sexual function is certain and entirely possible. Currently, we are familiar with the surgical operation of preserving the autonomic nerve, especially when TME is performed with care to protect the integrity of the sympathetic nerve trunk from the anterior aortic plexus and the parasympathetic nerve from the sacral nerve root, the overall incidence of impotence in patients after surgery can be reduced to 10-28%, and only 10-15% of younger men under 60 years of age will have impotence. According to foreign scholars, 78% of 77 male patients were able to maintain erectile function and sufficient for sexual intercourse after surgery, while erectile dysfunction was more common in male patients over 60 years of age, and 91% of 34 female patients were able to maintain sound sexual arousal. In conclusion, the current demand for improving postoperative quality of life has evolved from retaining only bowel control functions to three functions of defecation, urination and reproduction, and more towards the direction of normal human soundness.