Radionuclide therapy (RNT) uses the ionizing radiation generated by the emitted particles during radioactive decay to directly damage DNA structure or indirectly increase the concentration of free radicals in cells, thereby destroying or killing diseased cells. Radionuclides offer the advantages of high sensitivity, non-invasive, and functional imaging in clinical diagnosis. The key to RNT is to deliver sufficient radiation dose to tumors while reducing toxic side effects on normal tissues and organs. However, most radionuclides are unable to reach the lesion site, and the radiation dose is not sufficient to completely kill cancer cells. In recent years, the rapid development of nanotechnology has provided new ideas for the design of radiopharmaceuticals. Compared to small molecules, nanomaterials have the advantages of a larger specific surface area, more labeling sites, good biocompatibility, and a longer blood circulation time. Moreover, the combination of the unique intrinsic properties of nanomaterials with radionuclides can construct multifunctional carriers, which achieve mutual complementarity. In this paper, we summarize the research progress of nanomaterials in tumor radionuclide therapy (including radionuclide therapy, radionuclide/chemo therapy, radionuclide/immuno therapy, radionuclide/photothermal therapy, radionuclide/photodynamic therapy, and radionuclide/chemodynamic therapy) and prospect the future development and challenges of nano-radiopharmaceuticals.