According to WHO’s three-step pain relief principle, it is mainly divided into the following aspects: 1, the first choice for mild cancer pain is non-steroidal anti-inflammatory drugs, such as aspirin and acetyl amino acid, etc. 2, the first choice for moderate cancer pain is weak opioid drugs, such as codeine, and some non-steroidal drugs can also be added to codeine, which is called combination drugs. 3, the first choice for severe cancer pain is strong opioid drugs, such as morphine. For example, morphine, and then it is the principle of three-step treatment.