Abstract: Radiation therapy mainly kills tumor cells directly by inducing fatal DNA damage, and can also act on tumor tissues indirectly by activating host immune components, thereby inducing anti-tumor immune responses, but on the other hand, it can also lead to some immunosuppression. In recent years, the development of immune checkpoint inhibitors has shown a great therapeutic potential, especially the programmed cell death receptor-1 (PD-1) and programmed cell death ligand-1 (PD-L1) inhibitors, while it can't work in immune "cold" tumors. Based on the mechanism of action of radiotherapy and immune checkpoint inhibitors in tumor tissue, it was found that PD-1/PD-L1 inhibitors can relieve the immunosuppression induced by radiotherapy, allowing immuno "cold" tumors to be transformed into immuno "hot" tumors and thus benefit from immunotherapy. So, the combination of them has attracted extensive attention . In here, the author mainly introduces the mechanism of radiation therapy combined with PD-1/PD-L1 inhibitors and new progress was summarized, which is of great significant in selecting the right beneficiaries and estimating curative effect and prognosis.