Pain is a common symptom of cancer patients, and controlling cancer pain is an important element of palliative care, which is significant to alleviate patients’ pain and improve their quality of life. The following is the basic principles of World Health Organization’s three-step analgesia for cancer pain. 1.Oral drug administration Oral drug administration is adopted as far as possible. If oral drug administration is not possible (such as intestinal obstruction), fentanyl transdermal patch can be given, while intramuscular injection of morphine and dulcolax is not desirable. 2. Give the medication on time It is important to give the medication on time to maintain a stable blood concentration. Do not take the drug when the pain is present, stop taking it when the pain is relieved, and then take it again when the pain recurs, for this will not maintain the stable blood concentration in the body and the analgesic effect will be poor. 3.Giving medication according to the step Mild pain can be given non-steroidal drugs such as fenbuterol, futalin, etc.; moderate pain can be given weak morphine drugs such as codeine, tramadol, etc.; severe pain can be given strong morphine drugs such as methocarbamol, oxycontin, etc., and can be combined with non-steroidal drugs, such as neuropathic pain, can be combined with amitriptyline or gabapentin. Each patient has different causes and degrees of pain and needs different drugs and doses, so the best effect can be achieved by individualized administration. Pay attention to the side effects of analgesic drugs, such as vomiting and constipation, and routinely give anti-emetic and laxative treatment to minimize the side effects, which can improve patients’ compliance and quality of life. Cancer pain is treatable, and most of them can be relieved after standardized treatment.