High complex anal fistulas are relatively difficult to treat because of the high location of the lesion, the number of bent and complicated canals, and the frequent presence of branches and deep dead spaces. Improper treatment can lead to anal deformity, prolonged healing, recurrent attacks and even anal incontinence complications. Belliveau et al. showed that cutting the internal sphincter during fistula surgery only decreased the resting pressure of the distal anal canal, while cutting the external sphincter not only decreased the resting pressure of the anal canal, but also decreased the maximum systolic pressure and contractile force of the anal canal. Since the external anal sphincter plays a major role in anal restraint function, it should be protected as much as possible during surgery to prevent anal incontinence.Read used saline rectal irrigation in two groups of patients, and the rectal pressure in the group with self-control did not exceed the sphincter pressure, whereas the rectal pressure in the incontinent group exceeded the anal canal pressure, resulting in saline overflow, suggesting the dependence of anal self-control on the external sphincter.Sainia suggested that cutting the external sphincter Bartolo suggested that anal incontinence depends on the synergistic effect of various factors, the most important of which are the rectal angle of the anal canal and the anal canal pressure generated by the internal and external sphincters. Williams, through clinical investigations, found that the decrease in anal incontinence was related to the width of the fistula spread, the location of the internal orifice, and was proportional to the number of muscles incised during surgery; Chrirtensen, in the treatment of anal fistulas, found that scar tissue-induced anal canal defects were the main factor in anal incontinence after fistula surgery, rather than a decrease in anal canal pressure; scholars, in introducing the hanging wire method into Thomson incised the fistula from the anal verge to the internal orifice and drained the fistula via the external anal sphincter, removing the wire after the wound healed and closing the fistula. However, he believed that the role of the hanging wire was mainly to drain the fistula, followed by promoting fibrosis of the surrounding tissues and serving as a marker of the fistula, which was different from the concept of “Xu with a knife” in traditional medicine. The basic features of this procedure are: (1) no damage to the sphincter; (2) removal of only the fistula and preservation of normal tissue mainly of the sphincter; (3) appropriate drainage of the wound; (4) closure of the internal anal orifice defect. Dong Ping used the open drainage method for treatment and proposed the experience that an effective cure of anal fistula can be achieved by effectively changing the position of the internal orifice to move it outside the high pressure area. Huang Naijian et al. pointed out that after decompression of the internal orifice incision, intraoperative scratching of the canal and formation of fresh trauma, coupled with severe postoperative stimulation, the open canal could gradually heal with atresia due to connective tissue proliferation and less impact on anal fluid restraint function. Fan Yaming treated horseshoe-shaped anal fistula with simple internal incision and diversion, and for high-grade complex anal fistula, the part below the main rectal ring was accessed through diversion, the part above the main rectal ring was incised, and the residual canal was drained by hanging wires, which better protected the function of anal sphincter. Xi Xunqi et al. treated complex anal fistulas with tract root amputation, which can completely remove the primary lesion and effectively prevent recurrence. Wang Jin used the high virtual hanging drainage method to treat high anal fistula, and the function of the anorectal ring could be fully protected by the drainage and stimulation effect of the rubber band only. Li Wujiu et al. treated anal fistula with a minimally invasive triple method (local injection of the internal port, fistula embolization, and external pressure fixation of the wicker fistula), which greatly shortened the healing time and reduced postoperative pain. The medical staff of our anorectal department has long explored the treatment of high-grade complex anal fistula and learned that the following four aspects should be noted in anal fistula surgery: (1) thoroughly removing the lesion and finding the right internal opening; (2) minimizing the scope of surgical injury; (3) protecting the function of the anal sphincter; and (4) keeping the postoperative drainage unobstructed. In clinical practice, based on the inheritance of traditional surgical methods, combined with modern medical methods of dilation, drainage, irrigation and preservation of the sphincter muscle abroad, a set of surgical methods for the treatment of anal fistula with clinically proven efficacy has been developed, which are hereby introduced for clinical reference. 2.1 Open and open incision and drainage is suitable for those who have a low bronchial location and the main canal is located in the deep layer of the external sphincter. First, open the window of the external orifice of each branch and the external orifice of the main canal and enlarge the window appropriately, scrape out the rotten tissue in the fistula with a spatula from the open window, cut the main canal along the probe from 1.5-2 cm from the anal edge to about 2em above the dentate line, remove the rotten meat from the main canal with a spatula, expand the canal wall tissue as much as possible, and the wound is flared in a large external and small internal shape. until the wound is healed. 2.2 The open window is used for fistula tracts that are deeper than the external sphincter. The fistula tract above the hanging line is reopened and then left open; for higher branched tracts, the line can be hung close to the intestinal wall, and the tracts farther away from the wall are reopened and left open. The fistula tract is mainly used for drainage. 2.3 The open window and open wire catheter drainage procedure is suitable for fistulae located above the deep outer sphincter and with a large cavity. The skin and subcutaneous tissue are cut along the probe and the infected anal glands and sinus tissue are excised. For higher fistulas, the rubber band is clamped with a medium curved forceps and hung along the upper part of the fistula, about 2 cm above the dentate line. The wound should be flushed and changed daily, and the catheter should be removed when the wound is clear and the flushing fluid is clarified. 2.4 Open-window open diversion drainage is suitable for horseshoe-shaped anal fistula. If the incision is within 3cm from the anal verge, the probe can be inserted from the incision and probed out from the internal port. If the incision is more than 4cm from the anal verge, the probe can be probed out from the incision and probed out from the internal port. If this incision is more than 4 cm from the anal verge, the probe should be opened at 1.5-2 cm from the anal verge, and the incision should be expanded from the left, right and posterior side of the anus in three windows, and the posterior median can be cut to the tooth line, and the incision should be enlarged appropriately to facilitate drainage, and the fistula canal can be hung midway for deeper locations. If the wall of the tube is close to the intestinal wall, only the posterior side must be incised, and both sides may not be incised if there is no internal opening. In any case, the tube should be placed as straight and open as possible to facilitate drainage and drug exchange. If the middle of the fistula is close to the anal verge, the two ends should be cut in the middle. If the middle of the fistula is far from the anal verge, cut the middle and leave two ends. If the tube is deep, try to cut the upper layer instead of the lower layer to avoid cutting deeper and deeper. The extra-anal open fistula should be scraped out of the decaying tissue, part of the wall should be removed, and drainage gauze should be placed inside the fistula, which not only facilitates drainage and prevents adhesions, but also avoids anal deformity and ensures the integrity of anal function. At present, although scholars at home and abroad have made many useful attempts to treat high-grade complex anal fistulas, and have achieved some success in solving the contradiction between complete removal of the lesion, reducing the recurrence rate and protecting the self-control function of the anus, none of them is very mature and standardized, and the author hopes to conduct systematic clinical efficacy evaluation and experimental The author hopes to carry out systematic clinical efficacy evaluation and experimental research on this effective procedure for the treatment of high-grade complex anal fistula, to explore its mechanism, and to promote it to the society when conditions are ripe for the benefit of anal fistula patients.