Fentanyl, morphine and other drugs can be used for analgesic treatment of pain after anal fistula surgery. Slight pain after anal fistula surgery is a normal phenomenon, especially when defecation intensified, generally tolerable, need to pay attention to defecation accompanied by family members, so as to avoid pain caused by sympathetic and parasympathetic dysfunction, so that the blood pressure drops, heart rate slows down, and even the occurrence of collapse, shock and other dangerous conditions. Postoperative pain is unbearable or cause respiratory, urinary and cardiovascular system and other adverse consequences should be timely analgesic treatment, more drug therapy, commonly used drugs such as morphine, fentanyl, ropivacaine, etc., often using epidural analgesia, patient self-control analgesia analgesia and other analgesic methods. Postoperative pain and analgesia is very complex, patients with postoperative pain should promptly inform the doctor in charge or consult a professional physician to take appropriate measures, and follow the doctor’s instructions.