The anesthesiologist will formulate a reasonable anesthesia plan according to the specific surgical procedure, including: general anesthesia, intravertebral anesthesia, and nerve block anesthesia (the latter two are commonly known as “semi-anesthesia”), etc. Then the anesthesiologist will administer anesthesia to the patient after the patient enters the operating room, and then start the surgery. The anesthesiologist will adjust the depth of anesthesia to an appropriate level at any time according to the progress of the surgery and the patient’s condition until the end of the surgery, when the anesthesia will be reduced to a lighter level and the patient will be awakened. The above procedure means that the patient in the operating room does not have to worry about pain, but after the anesthesia wakes up, the patient will have more obvious postoperative pain. At this point, a reasonable and effective solution is the main task of “postoperative analgesia”. As we all know, while pain makes patients feel painful, it also produces a series of pathophysiological changes, such as affecting the autonomic nervous system of the body, making the heart rate increase, shortness of breath and blood pressure rise; affecting emotions, leading to irritability and depression, and then affecting the function of the digestive system and the recovery of physical strength; affecting endocrine and hormone levels, directly and indirectly disturbing the internal environment of the body. I. So what are the benefits of postoperative analgesia? It can be briefly summarized as the following points: 1. to reduce patients’ pain and discomfort, relieve anxiety and improve sleep; to enable patients to spend the postoperative period in a more comfortable state; 2. to eliminate the reluctance to take deep breaths and cough due to pain, improve breathing, promote sputum discharge and reduce lung infection; 3. to reduce pain and prompt patients to get out of bed early,, early functional exercise and reduce the risk of longer bed rest 4.Block sympathetic hyperexcitation, eliminate tension, dilate blood vessels, improve microcirculation, thus promoting wound healing and speeding up postoperative recovery; 5.Inhibit sympathetic activity, promote gastrointestinal peristalsis, and help restore gastrointestinal function after surgery; 6.Reduce hospitalization time and save costs by reducing complications and accelerating recovery. The basic process of postoperative analgesia is as follows: 1. The anesthesiologist assesses the postoperative pain index before or during surgery, or selects the appropriate postoperative analgesia according to the patient’s pain tolerance, explains the advantages and disadvantages of postoperative analgesia and the possible side effects and related costs to the patient or family and signs the consent form for postoperative analgesia; 2. 2. At the end of the operation, the anesthesiologist will use the appropriate analgesic equipment (commonly known as analgesic pump) and prepare the analgesic drugs, connect them to the corresponding input channels (intravenous analgesia and nerve block analgesia use intravenous indwelling needle, and intradural analgesia uses back epidural catheter), and open the self-control analgesia mode after the first analgesic dose is given; 3. However, due to individual differences in pain perception, a few patients will still feel more obvious pain, and then the patients can press the “self-control analgesia button” on the analgesic pump to administer additional medication, and most of them can significantly relieve the postoperative pain. The most intense postoperative pain is mainly within 36 hours after surgery, and the anesthesiologist is in charge of managing postoperative analgesia. Third, the correct understanding of the effect of postoperative analgesia: postoperative analgesia technique is to use continuous infusion of very low concentration of local anesthetics, analgesics and corresponding drugs that inhibit side effects to achieve the purpose of only blocking nociceptive nerves without affecting motor nerves, thus playing only analgesia without affecting movement. The evaluation of analgesic effect should not assume that the best analgesic effect is the complete absence of pain. Our goal is to significantly reduce pain, control postoperative pain within a range that patients can tolerate, and try to minimize the incidence of side effects. It is incorrect to think that if “analgesic pump” is used, it should be completely painless, because if it is completely painless, it is no different from anesthesia, and postoperative analgesia does not need to reach the level of anesthesia.