Anal fistula is spread to the inner thigh, if the abscess is not treated in time, the pus will be infected with the muscle gap to the inner thigh to form a fistula, and need active treatment. The main cause of anal fistula is the abscess around the rectum and anal canal breaks down on its own or cut and drained after the formation of the tube, if the fistula continues to recur, repeated infections, pus suddenly become more suggestive of a new fistula formation, the perianal area will be painful, swelling increased, pus will be infected along with the muscle gap spreading to the inner thighs. The fistula attack needs timely treatment, local drainage, to avoid the pus continues to spread to form a new fistula, through active anti-infection, standardized treatment, generally can control the development of the disease. The radical treatment of anal fistula requires surgery and hanging line treatment, remove the lesion, smooth drainage, as far as possible to protect the normal function of the anus. Patients need to standardize the treatment under the guidance of the doctor to avoid delays.