At present, laparoscopic radical rectal cancer surgery has been widely carried out in China, and it has become a routine procedure in some medical units. However, in clinical practice, there are still some issues that need attention and some difficulties that need to be further enhanced to understand and solve. Combined with the literature and our clinical practice, we will discuss a few points of understanding and experience. The incidence of IMA lymph node metastasis is 8% to 22%, and the 5-year survival rate is only 18.7% to 38%. In addition, proximal separation of the inferior mesenteric vessels is necessary to allow the free left hemicocele to enter the pelvis without tension. However, in clinical practice, high ligation of the IMA has been controversial at present. The reasons for this are mainly the following three considerations: First, it is difficult to achieve high ligation. In general, the beginning of the inferior mesenteric artery is often obscured by the upper duodenum, and to ligate the IMA in a high position, the duodenum must be pushed slightly upward to the right, which itself requires certain surgical revealing skills. Second, there are certain variants of the IMA itself, sometimes there are double IMAs with absence of the middle colonic artery and the transverse colon is supplied by a branch of the secondary IMA; there are also cases where the IMA is absent and the left colonic artery, sigmoid artery and superior rectal artery originate from the superior mesenteric artery or the middle colonic artery. Third, high ligation of the IMA may lead to ischemic necrosis of the sigmoid stump. Therefore, in our clinical work, our experience is that high ligation of the IMA does not necessarily have to be emphasized, but should be dealt with on a case-by-case basis. First of all, to ensure the blood supply to the sigmoid stump, it is best to ligate the left colonic artery after the IMA is divided, and in individual cases, only the superior rectal artery can be ligated. Of course, the lymph nodes adjacent to the IMA must be cleared. Total mesorectal excision (TME) was first proposed by Bill Heald et al. in 1982. After 30 years of clinical practice, TME has become the gold standard for the treatment of middle and low rectal cancer because it can effectively reduce the local recurrence rate of rectal cancer. Laparoscopic TME has more advantages than open surgery. (1) Laparoscopy has a magnifying effect on the narrow pelvic cavity, which makes it easier to judge the access, i.e., it is easier to enter the gap between the pelvic fascia and visceral wall layers; at the same time, it is more accurate in identifying and protecting the pelvic autonomic nerves. (2) The use of ultrasonic knife, i.e., sharp dissection, less bleeding, and more complete resection of rectal mesentery. tME must strictly follow the principle of whole resection, and the lymph nodes and tiny metastases that may metastasize next to the rectum are all wrapped in the rectal mesentery for complete resection, without making contact between the metastatic cancer tissue and the pelvic tissue left after resection, thus ensuring the completeness of rectal cancer surgery. In addition to reducing the recurrence rate of local tumors, TME surgery can lengthen the rectum by 3-5 cm after emphasizing the sharp separation of the anterior sacral area and separating the anterior rectosacral fascia under direct vision, thus making it possible to make low or super status anastomosis and thus improving the anal preservation rate. At the same time, TME requires the rectal mesentery to exceed the distal end of the tumor by 5 cm, which also improves the radicality. tME also provides the anatomical basis for preserving the autonomic nerve, which is necessary for the preservation of urinary and sexual functions and the postoperative quality of life of patients. In fact, the incidence of postoperative urinary difficulties and sexual dysfunction has decreased significantly since the introduction of TME for rectal cancer . It is generally believed that TME is suitable for patients with low to mid-stage rectal cancer of T1 to T3 with tumor invasion not exceeding the visceral fascia and no distant metastasis, and it is still controversial to perform TME for upper rectal cancer. TME requires resection of at least 2 cm from the distal bowel end of the tumor and at least 5 cm from the mesentery, and excessive resection of the mesentery often results in a higher incidence of anastomotic fistula, which is one of the problems of TME. Radical (R0) resection means complete resection of the rectal mesentery, no tumor residue at the cut end of the intestinal canal, and negative CRM, R1 resection means cancer residue under the microscope, and R2 resection means cancer residue under the naked eye. Laparoscopic TME for rectal cancer has become a standard operation and is widely used. At the same time, the use of laparoscopic APR for rectal cancer has decreased significantly. However, for rectal cancers within 6 cm from the anal verge, with low differentiation, especially for stage T3 to T4 or with fixed tumors, APR is still the main surgical approach. In order to reduce the local recurrence rate after APR, the concept of columnar APR was proposed by Swedish scholars. Studies have shown that even when APR is performed using the TME technique for the aforementioned low rectal cancer, patients still have a higher postoperative local recurrence rate and a lower survival rate. The reason is that the lower 1/3 of the rectum is completely covered by the rectal mesentery, which gradually thins out distally at the level of the starting point of the anal raphe, and gradually decreases and disappears above the sphincter, which is exactly where the low rectal cancer is located and where the rectal cancer is easily invaded with little sphincter resection, and is prone to positive circumferential margins and bowel perforation . In conventional APR, the abdominal dissection of the rectal mesentery reaches above the anal canal, where it is approached along the rectal mesentery toward the rectal wall, forming a narrow waist here, resulting in an insufficient resection area. The abdominal dissection of columnar APR ends with a sharp separation to the beginning of the anal raphe, and instead of freeing the rectal mesentery from the dissection, the anal canal, the anal raphe and the low rectal mesentery are removed from the perineum as a whole, so that the specimen becomes a column without a waist, ensuring that more normal tissues surrounding the tumor are removed together. Through practice, the application of columnar APR has reduced the rate of positive circumferential margins and bowel perforation, decreased the rate of local recurrence and, in turn, improved survival rates. Columnar APR operation in the perineum requires a change from the lithotomy position to a prone folding position, operating under direct vision, making perineal surgery easier. On the downside, pelvic floor reconstruction is usually required to prevent perineal incision complications during column APR surgery. The gluteus maximus flap can be used for repair, or biological materials can be used for reconstruction. For example, the use of decellularized allogeneic dermal matrix material to repair pelvic floor defects has achieved better results . Fourth, preservation of the pelvicautonomic nerveplexus (PANP) function has been the subject of intensive study to preserve the PANP as much as possible without affecting the radicality, to preserve the patient’s urinary and sexual functions, and to improve the quality of postoperative survival. In fact, in 1989, the Japanese Society of Colorectal Diseases officially affirmed that open surgery with preservation of PANP can ensure both the radicality of surgery and the preservation of normal physiological urination and sexual function of patients, but there is no evidence to support whether the radicality of laparoscopic rectal cancer and the preservation of PANP can be organically unified. From the principle of laparoscopic visualization, laparoscopy has a magnification effect, which is more advantageous in revealing the deep and narrow pelvic operative field, while separation and hemostasis with ultrasonic knife has the characteristics of small thermal damage area and less smoke, which is more conducive to the preservation of PANP and improves the efficiency of surgery . There is evidence that laparoscopic rectal cancer surgery has little difference in the incidence of urinary dysfunction compared to open surgery, but the incidence of sexual dysfunction is lower . Voiding and sexual function are primarily innervated by the pelvic sympathetic and pelvic parasympathetic nerves, with a small portion innervated by the pubic nerves. The pelvic sympathetic nerve is in charge of bladder sensation during urination, causing the internal sphincter to contract, inhibiting the detrusor muscle, acting as a urinary reservoir, and dominating ejaculatory function in sexual function; the parasympathetic nerve is also in charge of bladder sensation, causing the internal sphincter to relax and the bladder wall muscle to contract, acting as a urinary detrusor, and dominating erectile function in sexual function . Urinary dysfunction is manifested by delayed urination, slow urination, prolonged urination, interruption of urine line, residual urine volume greater than 50ml, inability to urinate on their own, and in mild cases, catheterization is still required 2 weeks after surgery, and in severe cases, catheterization can take up to 6 months. Sexual dysfunction is manifested by inability to have erection or poor erection, inability to ejaculate and abnormal sensuality, which is more obvious in male patients older than 40 years old.PANP consists of visceral branch of sacral nerve in the anterior lateral wall of pelvis and confluence with inferior ventral nerve, which is located at the level of seminal vesicle vessels or uterine cervix, and is a diamond-shaped dense nerve tissue patch, if middle rectal artery exists, this artery just crosses this structure, so middle rectal artery can be used as a marker to find Therefore, the middle rectal artery can be used as a marker to find PANP. The former is suitable for medium to highly differentiated rectal adenocarcinoma without invasion of the deep rectal fascia, without obvious lymph node metastasis in the pararectum, with a tumor diameter of less than 3 cm and an invasion of less than 1/3 of the intestinal circumference, and with complete preservation of the pelvic plexus and its afferent nerves, i.e. the sympathetic inferior ventral nerve and the parasympathetic visceral pelvic nerve. The efferent nerves, i.e., the bladder and prostate branches from the anterior superior horn, should also be preserved. The pelvic visceral nerve and the pelvic nerve should be preserved as they play a more important role in urination and sexual function. The pelvic visceral nerve and the posterior inferior corner of the pelvic plexus are at a certain distance from the deep rectal fascia and have relatively little chance of being invaded, and even if there is partial invasion, they can be partially preserved while the affected nerve is removed. When complete or partial preservation of the pelvic visceral plexus is also impossible, both sides or one side of the S4 pelvic visceral nerve should be preserved as much as possible because the S4 pelvic visceral nerve is the thickest nerve among the pelvic visceral nerves and can still maintain better urinary function after preservation. It has been shown that laparoscopic surgery is safe and feasible for low and intermediate rectal cancer and has been widely accepted clinically; laparoscopic surgery must have the same strict quality control as open surgery; laparoscopic surgery is significantly better than open surgery in terms of short-term postoperative results, such as recovery of bowel function, surgical infection, pain and length of hospital stay, but there is no significant difference between the two in terms of disease-free survival, overall survival and recurrence, etc. However, there was no significant difference in disease-free survival, overall survival and recurrence. In response, the European Society for Endoscopic Surgery developed guidelines for laparoscopic surgery for rectal cancer in 2011. Recent studies have shown that the long-term outcomes of laparoscopic surgery are comparable to those of open surgery in the treatment of low and intermediate rectal cancer, which is the best evidence that laparoscopic surgery will become the standard of care in the treatment of low and intermediate rectal cancer.