Extensive stage small cell lung cancer (ES-SCLC) has a poor prognosis and short survival. Although platinum based combined with etoposide regimens and prophylactic craniocerebral irradiation have become the treatment regimens for ES-SCLC, it still faces the challenges of low local control rate and overall survival rate. As a local treatment, radiotherapy has a wide range of applications, which can not only be used for the radical treatment of local lesions, but also for the selective palliative treatment of advanced patients. Thoracic radiotherapy can improve the local control of ES-SCLC, among them, patients with residual intrathoracic lesions after chemotherapy benefit the most. There is still no unified standard for the appropriate population, optimal dose and segmentation of thoracic radiotherapy, and further research is needed.