Complex anal fistula accounts for about 30% of all anal fistulas, and it is a common and difficult clinical disease due to its complex course, the large number of sphincter tissues involved, the difficulty of treatment, and the high recurrence rate. During the 11th Five-Year Plan, complex anal fistula was listed as a common disease in anorectology for key research. At present, the treatment is still mainly surgical, and most Western doctors use rectal mucosal flap nudging, fistula ligation, and staged incision and hanging, but there are different degrees of sphincter damage or cavity residue, pseudo-healing, etc., resulting in delayed healing or even recurrent attacks, which require multiple surgical treatments. Studies have shown that the recurrence rate of complex anal fistula is 15%-50% and the incontinence rate is 10%-60% after surgery, while the healing time can vary from 1 month to 16 months, and some of them even do not heal for a long time. Therefore, complex anal fistula has become a difficult and hot spot for research in the field of anorectal medicine at home and abroad, and good surgical efficacy and intact anal function have become a common goal for anorectal surgeons. Since the 1980s, the dragline therapy, which was founded on the basis of drug twisting therapy and thread hanging therapy, has been applied to the treatment of complex anal fistula and has achieved good results. For high fistulae and deep pus cavities, combined with the placement of drainage tubes, without cutting or hanging open the skin, tubes or excessive removal of surrounding tissues, especially muscle tissue, avoiding the risk of surgery, maximizing the protection of perianal tissue, effectively maintaining normal form and physiological function, minimizing skin defects caused by scar tissue, and avoiding sequelae such as incontinence; combined with the pad and cotton compression method in the late stage of treatment, more The fistula cavity closure is accelerated and the healing time is shortened. It has the advantages of high cure rate, low recurrence rate, wide scope of application, small tissue damage, fast healing of the sore surface, small scar, less pain, better recovery of function and shape after healing, and few sequelae.