Lung cancer is a common malignant tumor with the highest incidence and mortality rate among cancers. According to the histologic type of lung cancer, it can be divided into small cell lung cancer and non-small cell lung cancer. Non-small cell lung cancer, on the other hand, includes squamous carcinoma, adenocarcinoma (including large cell carcinoma) and bronchoalveolar carcinoma. Surgery, radiation therapy, chemotherapy and targeted drugs are all used for treatment at different stages and in different physical conditions. Among them, radiotherapy occupies a very important position in the treatment of both early and advanced lung cancer. 1. Radiation therapy for early stage non-small cell lung cancer. Surgical resection is preferred for early stage non-small cell lung cancer, and its 5-year survival rate is 40%-60%. However, for patients who cannot tolerate surgery due to advanced age, combined with medical diseases and refuse surgical treatment, radiation therapy is the best alternative means. Early stage non-small cell lung cancer can be cured in 50%-70% of patients by this method. I have treated 8 cases of early stage non-small cell lung cancer in the past two years, and except for 1 case that developed metastasis, the remaining 7 cases are still living healthily and have a good quality of life up to now. The current National Comprehensive Cancer Network (NCCN) guidelines have made body stereotactic radiotherapy a recommended treatment option for early stage lung cancer patients who cannot tolerate surgery.” 2, Radiation therapy for locally advanced non-small cell lung cancer. Locally advanced non-small cell lung cancer means localized spread without distant organ metastasis. For operable locally advanced patients, chemotherapy should be given after surgery, but for patients who are not operable for resection and can tolerate chemotherapy, simultaneous radiotherapy is the first choice, which can not only improve the local control rate, but also reduce the chances of distant metastasis, thus improving the prognosis of patients. Reports show that synchronized radiotherapy can make 20%-30% of patients survive for more than 3 years. 3.Radiation therapy for advanced non-small cell lung cancer. In advanced non-small cell lung cancer, there are metastases to distant organs, such as brain, bone, etc. Chemotherapy is the first choice for this kind of patients. Chemotherapy is the first choice for this kind of patients, but radiotherapy also plays an important role in the process of treatment, which can not only reduce pain and improve the quality of life, but also prolong the survival time of patients. For patients with brain metastasis of non-small cell lung cancer, radiotherapy is more important, because chemotherapy drugs cannot enter into the skull through the blood-brain barrier, and often chemotherapy is ineffective, and the use of craniocerebral radiotherapy can obviously prolong the survival time of patients and improve the quality of life. According to the study, patients first diagnosed with lung cancer accompanied by intracranial metastasis have poorer prognosis, and the median survival of untreated patients is only 1-3 months, while the median survival of patients treated with radiotherapy can reach 8-10 months. For patients with bone metastases, pain is the most important symptom, which obviously affects the quality of survival, but if a certain dose of radiotherapy is given, nearly 80% of patients can be relieved.