With the development of nanomaterials and nanotechnology, nanomedicine possesses the vast application prospects in the field of cancer therapy. Although the proportion of radiotherapy in cancer comprehensive therapy is rising, the radiotherapy resistance of cancer cells and the side effects of radiotherapy are the existing problems. Compared with the traditional radiotherapy sensitization, it will present a higher treatment efficiency and lower toxicity to introduce nanomaterials and nanotechnology to cancer radiotherapy. This review elaborates the research of nanomaterials and nanotechnology on cancer radiotherapy sensitization.