Postoperative pain is a complex physiological-psychological response of the body to the process of tissue damage and repair, and is seen in almost all postoperative patients. With the in-depth research on the basic theory of pain, there are many new insights into the mechanism of postoperative pain generation and treatment. In clinical work, pain has become the fifth vital sign after the four vital signs of body temperature, pulse, respiration, and blood pressure, and in recent years, postoperative analgesia has been taken as one of the routine elements of clinical work abroad. Finger severance injury is a common and frequent disease in hand surgery, and the treatment method is to perform finger replantation. Due to the richness of nerve endings in the fingers, postoperative pain is very severe, which affects the diet and sleep of many patients, and the patient feels the “ten fingers are connected to the heart” very deeply, so postoperative pain relief becomes an important issue in hand surgery. Dizocine is a potent opioid analgesic that can relieve postoperative pain, and its analgesic strength, onset and duration of action are comparable to those of morphine, but its addiction is minimal. From May 2012 to the present, dizocine injection has been used to treat postoperative pain after finger reimplantation with satisfactory efficacy. Postoperative pain is different from general physiological pain, and in addition to mechanical injury to nerve endings caused by trauma, altered sensitivity of peripheral nerves and central nervous system is the main cause of postoperative pain when tissues are damaged. Injury stimulation causes reverse cytoplasmic flow in the axons of peripheral nerve cells, resulting in the release of substance P from nerve endings, causing increased local vascular permeability and tissue edema; at the same time, inflammatory pain-causing substances released from damaged tissues, such as bradykinin, histamine, leukotrienes, prostaglandins and some other arachidonic acid metabolites, cause inflammatory reactions, which can both directly stimulate injury receptors and cause peripheral nerve activation and sensitization, which can produce pain even with normal subthreshold stimulation. Recent studies have shown that due to surgical injury and some other noxious stimuli in the perioperative period, the excitability of the neurons in the dorsal horn of the spinal cord is increased, forming an enhanced central sensitivity, which increases the intensity of the central nervous system response to painful stimuli and prolongs the time frame, while some non-painful stimuli can also cause severe pain. It is thus clear that postoperative pain is an over-sensitization of nociception and the abnormal spread of this sensitivity to the tissues surrounding the injury. The most important aspect of postoperative pain on physiological function is the visceral reaction, mainly related to the abnormal autonomic activity caused by pain and the elevation of catecholamines in blood, which is preceded by the abnormal activity of vegetative nerves and causes a series of organ and tissue reactions; manifested as increased blood pressure, accelerated heart rate, heart rhythm disturbance, or even cardiac arrest; shallow and rapid breathing; nausea, vomiting, sweating, etc., and also The abnormal release of pain-causing mediators can aggravate the ischemia, hypoxia and edema of the severed finger after surgery, and cause abnormal metabolism of hormone and enzyme systems, slow protein synthesis and accelerated decomposition, which is not conducive to wound healing. In addition, pain can cause a decrease in immunoglobulins and affect postoperative recovery. Especially after thoracotomy and upper abdominal surgery, patients with deep incisions and damaged nerves in the chest wall are reluctant to cough, breathe deeply and turn over, making it easier to form complications such as pulmonary atelectasis, thrombosis and paralytic intestinal obstruction. Postoperative pain is the main cause of postoperative complications, and postoperative pain seriously affects postoperative rehabilitation and quality of life of surgical patients. Effective relief of postoperative pain has significant significance in improving prognosis and shortening hospital stay. Since the formation of postoperative pain is not only related to peripheral nerve sensitization, but also recognizes central sensitization as an important mechanism of pain formation, the aim of postoperative pain relief is to inhibit or reverse the altered excitability of central neurons caused by afferent nerve impulses, rather than requiring the achievement of complete disappearance of physiological and pathological nociception. Opioids such as morphine, diazoxide, and fentanyl bind to opioid receptors in the nerve center, activating the central part of the endogenous analgesic system in vivo and inhibiting the upward transmission of injurious information to the dorsal horn neurons of the spinal cord, either directly or indirectly through downward inhibitory fibers, thus providing analgesia. Opioids have been the primary method of postoperative pain relief since their discovery. Dizocine is a phenmorphanolane derivative that primarily agonizes κ receptors, which are distributed in the brain, brainstem and spinal cord, and agonizing κ receptors produces spinal analgesia, mild sedation and respiratory depression. According to the pharmacokinetics of dizocine and the dose prescribed by the national pharmacopoeia: the postoperative drug formulation of dizocine in the intravenous analgesic pump injection group was dizocine 0.8mg/kg plus saline to 100ml continuous intravenous analgesic pump injection (2ml/h); in the control group, dulcolaxin 1.5mg/kg plus saline to 100ml continuous intravenous pump injection (2ml/h). A controlled study confirmed that dizocine had better analgesic effect compared to the traditional analgesic dulcolax. The intravenous pump injection of dizocine facilitates the maintenance of a prolonged and stable drug concentration in the body relative to intramuscular injection, with better postoperative analgesia and longer duration of action. In addition, in this study, we observed that two patients in the diazoxide analgesia group developed respiratory depression, one of them was an older (65 years old) patient with a weaker body and the other was a younger (8 years old) patient, so the dosage of diazoxide should be reduced in some special groups to prevent complications. The fact that none of the cases in the diazoxide group showed occultation fully indicates that it is less addictive and can be used clinically with confidence in young and strong patients.