Background　Opioids and its regulatory mechanism are hot spots in the study of immune regulation. It is very important to study the mechanism of interactions among different kinds of cells and tissues, which have the dual character in regulating immunity.　Objective　The latest progress in the study of immune system of mu receptor and its mechanism for the treatment of cancer pain is taken into account for providing a new strategy for tumor immune regulation.　Content　Recent studies have found that opioids and their downstream targets are involved in the regulation of the development of different diseases, especially the study of mu opioid receptor is abundant. It can regulate the function of immune cells directly, subsequently regulate the innate and specific immune responses. In addition, there is an interaction between the receptor and the immune system, which plays an important role in immune regulation.　Trend　μ opioid receptor regulates role in immune optimization of novel opioid drugs. For the treatment of cancer pain and tumor, immunotherapy provides a new direction for clinical treatment.