Pain symptoms; advanced pain is one of the most common symptoms of cancer patients, which seriously affects the quality of life of cancer patients. The incidence of pain in first diagnosed cancer patients is about 25%; the incidence of pain in advanced cancer patients is about 60%-80%, and 1/3 of them are in severe pain. If cancer pain (hereinafter referred to as cancer pain) is not relieved, patients will feel extremely uncomfortable, which may cause or aggravate anxiety, depression, fatigue, insomnia, loss of appetite and other symptoms, seriously affecting patients’ daily activities, self-care ability, interaction ability and overall quality of life. Pain is divided into two main types according to pathophysiological mechanisms: injury-receptive pain and neuropathic pain. (1) Injury-receptive pain is pain caused by damage to the body or organ tissues due to the action of harmful stimuli. Injury-receptive pain is associated with actual or potential tissue damage, and is the process of physiological nociceptive nerve information transmission and response that the body exhibits in response to injury. Injury-receptive pain includes somatic pain and visceral pain. Somatic pain often presents as dull, sharp, or pressure pain. Visceral pain usually manifests as diffuse pain and colic that is not sufficiently localized. (2) Neuropathic pain is caused by damage to peripheral or central nerves and abnormal nerve impulses in nociceptive transmission nerve fibers or pain centers. Neuropathic pain is often presented as stabbing pain, burning pain, discharge pain, shooting pain, numbness pain, paresthesia pain, shooting pain. phantom pain, central drop, and swelling pain, often combined with spontaneous pain, touch-evoked pain, nociceptive hypersensitivity, and nociceptive hypersensitivity. Chronic pain after treatment is also classified as neuropathic pain. Pain is divided into acute pain and chronic pain according to the duration of onset. Most of the cancer pain is manifested as chronic pain. Compared with acute pain, chronic pain lasts longer, the etiology is not clear, the degree of pain and the degree of tissue damage may be separated, and it may be accompanied by nociceptive hypersensitivity, abnormal pain, and poor efficacy of conventional analgesic treatment. The mechanisms of chronic pain and acute pain have both commonalities and differences. In addition to the basic conduction modulation process of injury-receptive pain, chronic pain can also exhibit neuropathic pain mechanisms that are different from acute pain, such as injury receptor hyperexcitability, ectopic electrical activity of damaged nerves, over-sensitivity of central mechanisms of nociceptive transmission, abnormal expression of ion channels and receptors, and central nervous system remodeling.