The cancer pain, as one kind of chronic pain, seriously affects the life quality of patients. Morphine is commonly used for cancer pain treatment, but tolerance development limits its clinical administration. In this review, we introduced the mechanism of cancer pain and the mechanism of morphine tolerance in cancer pain treatment, and we clarified the interaction between the mechanism of cancer pain and the mechanism of morphine tolerance in the process of the cancer pain‑morphine tolerance and the mechanism of the cancer pain‑morphine tolerance to provide a reference for the cancer pain treatment and the prevention and treatment of morphine tolerance in cancer pain treatment.