Surgical resection is the most important treatment of thymoma. However, the role of postoperative adjuvant radiotherapy (PORT) has been controversial. The survival benefits of two-dimensional radiotherapy are not significant. However, precision radiotherapy has significantly changed tumor radiotherapy. The value of PORT for thymoma may also be altered. At present, the effect of radiotherapy in patients with positive surgical margins or inoperable resection is confirmed. For patients with complete surgical resection, Masaoka-Koga stage Ⅰ patients do not require PORT. Whether PORT should be given for stage Ⅱ patients remains debated if stage Ⅱ_b, large volume and B2/B3 type were considered during radiotherapy. The role of PORT for stage Ⅲ patients is also in disputed, whereas a majority of findings support the application of PORT. Precision technology is recommended during PORT. The clinical target volume suggests that the three-dimensional expansion of the tumor bed is 0.5 cm, including the mediastinal pleura involved by the tumor and 0.5-1.0 cm along the anterior and posterior direction of the mediastinal pleura, the cranial and caudal direction, the lung side is expanded within the 0.5 cm, and the vascular wall around the tumor and part of the vascular space, so as to avoid including too much normal tissue. The dose for complete resection is 45-50 Gy and 54-60 Gy or slightly higher for incomplete resection, which may increase the benefits and reduce the risk of PORT.The application of new radiotherapy techniques such as particle therapy can gain the advantage of dosimetric distribution, and whether it can be transformed into clinical benefits needs to be further explored.