Radiotherapy is effective and widely used in the treatment of head and neck, chest, abdominal, and hematologic tumors. Radiotherapy, or radiation therapy, is a local treatment modality that applies radiation to treat oncological diseases. At present, the radiation that can be applied includes α, β, γ rays produced by radioisotopes and X rays, electron beams, proton beams and other particle beams produced by various types of X-ray therapy machines or gas pedals. Radiotherapy is widely used in a variety of oncological diseases, such as nasopharyngeal cancer, glioma, esophageal cancer, non-small cell lung cancer, gastric cancer, colorectal cancer, prostate cancer, breast cancer, ovarian cancer, uterine cervix cancer, and other solid organ tumors, and it can also be applied to non-Hodgkin’s lymphoma and other hematological system tumors. In conclusion, as one of the tumor treatments, radiation therapy plays an important role in neoadjuvant therapy, radical therapy, and palliative and other treatments. Whether or not to apply radiation therapy in clinic also needs to be combined with the sensitivity of the disease itself to the treatment. Therefore, it is recommended that patients go to specialized hospitals in time.