According to the statistics, there are more than 7 million cancer patients in China, 51%-62% of them have different degrees of pain, and 60% of them have moderate to severe pain, so pain has become one of the main killers of human health. Pethidine (Dulcolax) is an opioid commonly used in clinical practice, with analgesic and anesthetic effects equivalent to 1/10-1/8 of morphine, and the duration of action is 2-4 hours. The side effects of pethidine are relatively mild, such as nausea, vomiting, constipation, etc. The inhibitory effect on the respiratory system is weak, and the problems of respiratory distress and overdose generally do not occur, so it has long been chosen by many clinicians for pain relief of cancer patients. However, in recent years, the standardized cancer pain treatment standards at home and abroad have clearly pointed out that pethidine is prohibited for the pain treatment of advanced cancer patients. WHO has clearly stated that pethidine hydrochloride is not suitable for the treatment of moderate to severe cancer pain, and has taken the use of pethidine hydrochloride as a criterion to measure the level of cancer pain treatment, and the more pethidine hydrochloride is used, the lower the awareness of cancer pain treatment. The reasons are: (1) the effective analgesic time of pethidine hydrochloride is short, generally 2-4 h; (2) its metabolite, norethindrone, is neurotoxic and can produce tremor, convulsions, myoclonus and grand mal seizures with long-term use, and is not antagonized by naloxone; (3) it can reduce myocardial contractility and cause a decrease in blood pressure; (4) subcutaneous or intramuscular injection may cause local inflammation and tissue sclerosis, and repeated injection (5) The concentration in the blood and then in the brain rises rapidly after injection, and it is easy to reach the high concentration that causes the feeling of “floating”, which is the main reason why the drug is prone to abortion. Therefore, the Ministry of Health of China has clearly stipulated that the use of pethidine hydrochloride is contraindicated in patients with cancer pain. The WHO advocates that oral morphine controlled-release dosage form (mescaline) is preferred for cancer pain treatment, and its analgesic time can be maintained for 12 h. The controlled-release technology avoids the fluctuation of drug concentration in the blood, and its use according to therapeutic principles generally does not bring euphoria (“addiction”). The Principles of Clinical Application of Narcotic Drugs issued by the State Ministry of Health in 2007 clearly stipulates that “there is no limit to the amount of opioid analgesics (e.g. morphine) for long-term use in advanced cancer, i.e. the dose should be decided according to the individual’s tolerance level of morphine and other opioid analgesics, but close attention should be paid to monitoring adverse reactions. Injectable prescriptions should not exceed 3 days’ dosage, controlled (extended) release prescriptions should not exceed 15 days’ dosage, and prescriptions for other dosage forms of narcotic drugs should not exceed 7 days’ dosage.” In standardized cancer pain treatment, pain assessment should be carried out first, and analgesic drugs should be given according to the assessment results according to the three-step principle, and attention should be paid to the observation of pain-relieving effects and drug side effects, and the dose should be reduced or stopped in time when abnormalities are found. Commonly used drugs include non-steroidal anti-inflammatory drugs, opioid analgesics and adjuvant drugs, and special attention should be paid to the following principles when administering the drugs: (1) administering drugs according to the principle of three steps: the first step is to treat mild pain with paracetamol, aspirin or other non-steroidal anti-inflammatory drugs, and if the pain increases, the second step can be used. The representative drug for second-step administration is codeine. The first and second step drugs have a maximum effect (i.e. ceiling effect) when used, and if the pain is still not controlled, the third step drug should be chosen. The third step drug is morphine, and this step drug has no “ceiling effect”. If the patient’s pain is already moderate at the time of consultation, the treatment should be started from the second step, and the order of treatment should not be reversed. (2) Timely dosing: The medication should be given at prescribed intervals, such as every 12 hours, regardless of whether the patient is experiencing pain at the time, rather than on demand. (3) Individualized dosing: sensitivity to narcotic drugs varies greatly among individuals, so there is no standard amount of opioids. Any dose that relieves make pain and has no serious side effects is the correct dose. (4) Oral administration: oral administration is the most common way of drug delivery, which is convenient, economical and has strong patient compliance, but has first-off effect. Oral administration should be preferred for cancer pain, and other routes of administration, such as rectal administration, skin patch and intravenous injection, should be considered only in cases of severe nausea and vomiting and inability to swallow.