Pain is the main and initial symptom of bone metastasis, which accounts for the first place of cancer pain and is often intractable. In view of the fact that bone metastases are mostly in the advanced stage of tumor, conservative treatment is the basic principle. Although there are more pain-relieving drugs and they have good pain-relieving effects, the efficacy is short and easy to produce dependence. Radiation therapy has a definite pain-relieving effect on bone metastases, especially the recent effect is very significant and long-lasting. Radiotherapy can not only achieve the purpose of pain relief, but also stop the development of local lesions, shrink the tumor, reduce the pressure on surrounding tissues, improve the patient’s mobility and prolong the survival period. It can also increase collagen synthesis by killing tumor cells through radiotherapy, and promote the healing of destroyed bone due to the formation of fibrous matrix and the increase of osteoblast activity to form new bone. To achieve pain relief and control the development of tumor, it is necessary to increase the dose of local irradiation, which seems to cause damage to the adjacent organs. How to protect the normal organs and achieve the dose that can control the tumor development is a problem for radiotherapists to consider. In recent years, the clinical application of 3D conformal irradiation technology has solved these problems. In particular, 3D conformal intensity modulated radiotherapy can protect the spinal cord during radiotherapy for metastatic cancer of the spine in a way that other techniques cannot. It is a safe and effective radiotherapy method for the treatment of limited bone metastases. Irradiation dose and segmentation method for pain relief of radiotherapy for bone metastatic cancer: Randomized studies using different dose segmentation schemes have been reported in the literature to show no significant difference in pain relief. We observed that single high-dose radiotherapy provided pain relief earlier than conventional segmentation irradiation. Hypofractionated radiotherapy is simpler and easier than conventional radiotherapy and provides rapid pain relief, which is especially suitable for those with short expected survival, poor general condition and severe pain, avoiding the pain of moving due to daily radiotherapy. Bone metastasis is a late manifestation of tumor and has a poor prognosis, but patients with single limited metastasis still have some therapeutic value for this disease through local radiotherapy, especially the three-dimensional conformal irradiation technique. According to the author’s observation, for cases limited to bone metastases only, the recent pain relief effect reached 100% after 3D conformal radiotherapy, and some patients obtained long-term survival, while the damaged bone was restored, and no severe pain occurred again in the metastases treated by radiotherapy.