Pain is the late manifestation of many malignant tumors, and drug therapy is the main method of cancer pain relief. The following principles must be followed for cancer pain relief medication: 1. Use medication according to a ladder: the selection of pain medication should be gradually increased from weak to strong according to the pain degree. Firstly, choose non-opioid painkillers, the representative drug is aspirin, which is used for mild pain and is the first-step pain relief. If first-step pain relief is unsatisfactory, use second-step pain medication (representative drugs are codeine, chimantine, OxyContin, etc.), which is a weak opioid pain medication added to non-opioid pain medication. If second-step pain relief is not satisfactory, use third-step pain medication (representative drug is morphine), i.e. strong opioid pain medication plus non-opioid pain medication. Non-opioid analgesics can increase the pain-relieving effect of opioid analgesics, especially for patients with bone pain and neuropathic pain, and can reduce the dose of opioid analgesics. Adjuvant medications can improve other symptoms that often occur in patients with cancer pain. The following diagram shows the pattern of three-step pain relief: Pain Occurrence First step ↓ Mild pain → non-opioid drugs ± adjuvant drugs ↓ Unsatisfactory pain control ↓ Second step Moderate pain → weak opioid drugs + non-opioid drugs ± adjuvant drugs ↓ Unsatisfactory pain control ↓ Third step Severe pain → strong opioid drugs + non-opioid drugs ± adjuvant drugs 2.Timely medication: pain relievers should be given regularly and on time, not when the pain occurs again. Do not wait until the pain occurs again. It should be given before the previous drug effect disappears to maintain the effective blood concentration and effectively relieve pain and control pain. 3. Preferred oral administration: Oral administration should be preferred for patients who receive long-term pain treatment. Oral administration is economical, convenient, effective and with small payment effect, and patients can master it by themselves without the help of others. Oral administration of opioids is slow in absorption, low in peak value, and does not easily produce drug dependence. If the patient is vomiting severely, coma, swallowing difficulties, can not be given orally, can choose external methods, such as rectal administration. 4, individualized principle: individual sensitivity to opioids is different, there is no fixed standard dose, the patient’s drug dose should be to achieve effective analgesia as the standard, should not be limited by the so-called extreme amount. If the dosage of morphine is chosen between 10-60mg, the majority of patients can relieve pain, and the dosage of individual patients can be up to 200-400mg. The appropriate individualized drug dosage should be figured out for each patient.