The clinical causes of cancer pain are many and complex. From the causes of advanced tumor pain, about 65% of the pain is related to tumor, 25% of the pain is related to treatment, and the pain caused by other factors accounts for about 10%. 1. direct compression and stimulation of nerves by tumor; 2. skeletal metastasis of tumor; 3. stimulation of pain-sensitive tissues (blood vessels, lymphatic vessels, etc.) by tumor; 4. pain caused by tumor secretory factors, pain caused by accompanying inflammatory factors; 5. pain after surgery, radiation therapy, chemotherapy and other treatments; 6. psychological factors. Nature and degree of advanced cancer pain 1.Continuous occult pain and distension are the most common manifestations of advanced tumor pain, mostly seen in the early stage of various visceral tumor pain; 2.Continuous occult pain accompanied by paroxysmal pain is the clinical manifestation of pain in cavity organs or invasion of liver and bile ducts; 3.Continuous pain accompanied by spontaneous pain may be the clinical manifestation of pain in invasion of peripheral nervous system tumor; 4.Moderate or above Persistent pain accompanied by paroxysmal pinprick-like, fasciculation-like, knife-like or electric shock-like pain may be the clinical manifestation of metastatic pain of nerve roots and plexus; 5.With burning-like pain may be the result of invasion of sympathetic nervous system. 6.If the patient presents with pressure pain in multiple parts of the sternum or ribs, and also occurs with wandering pain involving multiple joints of the elbow, wrist, knee and hip, be alert to leukemia and multiple myeloma.