Abstract: Radiotherapy is one of the three conventional methods for the treatment of malignant tumors. However, its expected effect is not often achieved because of some limitations, such as normal tissue damage by high radiation dose and the radiation resistance of tumor cells. Thus, exploring new strategies for new radiosensitizers and radio-chemotherapy agents has become a research focus to improve the efficacy of radiotherapy and reduce its side effects on normal tissues. Polymer nanomaterials have broad application prospects in improving the effect of radiotherapy because of their excellent biocompatibility and physiological stability. This article reviews the research progress on polymer nanomaterials for radiosensitization.