Postoperative analgesia has become an important part of the surgical treatment process, enabling many patients to easily pass through the wound pain period after anesthesia disappears, helping patients to turn over and move around early and even get out of bed, and helping patients with upper abdominal and thoracic surgery to cough and excrete sputum, promoting the recovery of lung function and reducing the occurrence of pulmonary complications. Postoperative analgesia is generally divided into epidural analgesia, intravenous analgesia and subcutaneous analgesia. Epidural analgesia was first developed, and the main drugs are local anesthetics plus small doses of opioid analgesics, intravenous analgesics are mainly opioid analgesics, and subcutaneous analgesia mainly uses opioids that are more fat-soluble and easily absorbed through the skin. The main side effects of postoperative analgesia include skin itching, nausea and vomiting, urinary retention, and some patients may experience drowsiness and dizziness, but these side effects can be controlled or avoided through appropriate treatment, and the side effects of analgesia are acceptable to the majority of patients compared to the pain after surgery. In addition, since there are some opioids in analgesics, some patients worry whether they will become addicted, which is totally unnecessary, because it is a purposeful short-term continuous medication, and there are strict procedural norms for dosage and usage, and more importantly, the recipient is a patient who needs treatment.