Fentanyl is a potent anesthetic analgesic, usually used for various pains, postoperative analgesia, patient-controlled analgesia and anesthetic assistance because of its rapid onset and short maintenance time. For extracorporeal circulation surgery, the general dose is 0.02 mg/kg, and the maintenance dose is half of the initial dose. For patient-controlled analgesia, the starting analgesic dose is 0.19-2mg/d. In addition, it should be noted that bronchial asthma, respiratory depression, those who are particularly sensitive to this product and patients with severe myasthenia gravis are prohibited before use.