If lung cancer patients experience moderate to severe pain that severely affects the quality of life, morphine-like drugs may be considered for powerful analgesia. Morphine can be given orally or subcutaneously. Giving morphine-like drugs needs to be administered on a regular schedule and not on demand. Giving morphine orally or subcutaneously at a fixed time improves the bioavailability of the analgesic drug, and on-demand administration does not provide rapid analgesia. Morphine has the side effects of respiratory depression and constipation, so the patient’s pulmonary function and respiratory status need to be closely monitored during the long-term administration of morphine-based analgesics. If respiratory depression and pupillary constriction occur, morphine toxicity should be alerted, and the dose of morphine should be adjusted or replaced by other analgesic drugs to avoid morphine harming the body and posing certain risks to patients’ lives. In conclusion, the effect of morphine in treating lung cancer pain is relatively ideal, and its side effects need to be closely observed.