Anal fistula, also known as anal leakage, is an abbreviation for anorectal fistula, which is an infectious disease of the perianal rectum, mostly septic infection, and rarely tuberculosis. Complex fistulas are difficult to operate and easily damage the anorectal ring and anal sphincter due to the special anatomy and function of the lesion site, and are prone to recurrence after surgery, making them difficult to treat. There are many surgical treatment methods for complex anal fistulas, and currently they are treated by incision and hanging, incision and internal drainage, fistula removal and suturing, and fistula openings. The length of the incision is determined by the depth of the fistula in order to achieve adequate drainage. The mucosa on both sides of the internal opening is ligated with silk thread to thoroughly cleanse the infected anal sinus, anal glands and anal ducts. The sphincter on the side of the rectus ring where the tube passes through the internal orifice is hung with a rubber band, and if the internal orifice is at the 6 o’clock position, the posterior lateral dentition is probed for the internal orifice or suspected anal sinus and incised together with the posterior side. Use curved forceps to separate the fistula main tube and branch tube, the index finger is easy to enter and exit the degree, scrape the spoon to remove all necrotic and granulation tissue, and hang with a 2cm wide rubber drainage strip. 2, cut and sew internal drainage: start from the external mouth along the fistula tract, the main tract through the rectal ring of the anal canal can be cut together if it is fibrotic, and the part of the rectal ring of the anal canal that is not fibrotic is treated with hanging thread. The canal and pus cavity are thoroughly scratched, the corrupt tissue of the canal is removed, and the canal wall is properly trimmed, but it is not necessary to remove all of them to avoid excessive local tissue defects and to facilitate traumatic adhesions. Then the anal sinus and anal gland ducts around the internal opening and the infected anus were thoroughly removed, and the mucosa on both sides was ligated to prevent bleeding. The wound is flushed, and the radial incision (about 1.5 cm long) at the endo-oral canal is extended and left for drainage, while the rest of the incision is closed with silk sutures in full layers, leaving no dead space. If the pus cavity is too large, you can put a rubber band to drain it for 24 hours and pull it out. 3.Fistula removal suture: remove all the fistula from the external mouth along the fistula tract, stop bleeding thoroughly, flush the wound, and then close the wound with full interrupted suture or “8” suture, or “U” suture. The anal canal is closed with fine intestinal sutures, and the anal margin is closed with silk sutures. 4.Fistula openings: make a wide incision around the internal opening, the incision should be deep enough to cut the internal and external sphincter, if the fistula is semi-horse-shoe, cut the posterior anal space at the same time, scrape the pus cavity and canal, trim the scar tissue, the residual part should also make multiple incisions to soften the scar, and remove the excess skin on both sides of the external opening. Complex anal fistulas are those with two or more internal or external openings, two or more fistulas or branched or blind ducts. High complex anal fistula is more difficult to treat because of the high lesion site, complex bending of the canal, and the presence of branches and deep dead cavities. 1, incision and hanging has a surgical operation is easy, little damage, drainage is smooth; tube lumen rubber open, the use of autoimmune repair, and make the wound in an aerobic environment to facilitate wound repair; change of medicine only dragging latex rubber strip, you can bring out the fistula necrosis and granulation tissue, and reduce the change of medicine to take fill gauze pain. However, because the tissue is inside the rubber band, the pain is heavier and often lasts 24 hours or more, and there is a foreign body sensation. 2, incision and suture endograft drainage shorten the treatment time, less painful when changing medication, the branch is not easy to completely remove, drainage is not smooth, easy to recur. 3.Fistula removal and suturing has shortened treatment time, prevented anal deformation and protected anal function, but it is easy to recurrence of infection and prolonged treatment time after failure. 4.Fistula open suturing preserves the sphincter and reduces tissue damage. In summary, I believe that the use of incisional internal drainage and fistula removal suture is better for low complexity fistulas, while the use of incisional hanging and fistula placement is better for high complexity fistulas. During the perioperative period, attention should be paid to: correct search and treatment of the internal orifice, the search must be gentle, so as not to cause a false internal orifice, and the internal orifice should be drained smoothly. Hanging threads during incision and hanging, try to protect the rectal ring of the anal canal to prevent anal incontinence; drainage is unobstructed, the amount of drainage to decide to take rubber strips and rubber bands, less is taken early, more is taken late. The fistula must be excised thoroughly and the wound closed without leaving any dead cavity or foreign body; the former is drained smoothly to avoid pseudo-healing. The fistula is scraped thoroughly to remove all necrotic tissue and granulation from the fistula. Postoperative antibiotics are routinely given to prevent postoperative wound infection, especially for fistulas with branched tubes or small amounts of pus, and effective and adequate antibiotics should be given based on the results of bacterial culture muscle drug sensitivity tests. Keep the wound and the wound surface dry and clean with timely and correct drug changes. If necessary, herbal sitz baths can improve local blood and lymphatic circulation, reduce tissue edema, and promote granulation growth to achieve the effects of anti-inflammation, swelling, pain relief, and healing.