The difference between radiotherapy and chemotherapy for lung cancer can be manifested in the application principle, applicable population, contraindicated population and so on. The scope of application of chemotherapy is wider than that of radiotherapy. 1. Application principle: radiotherapy refers to eliminating or eradicating tumor lesions through radiation. Chemotherapy refers to killing cancer cells through oral or injected drugs, so as to achieve the purpose of treatment. Chemotherapy belongs to systemic treatment, while radiotherapy belongs to local treatment. 2. Applicable people: radiotherapy is usually applied to patients with advanced stage of lung cancer, old age and cardiopulmonary insufficiency. Chemotherapy usually runs through the whole treatment stage and is applicable to the early and late stages of lung cancer, which is more widely applicable. 3. Contraindications: Radiotherapy is not suitable for patients with serious heart, liver and kidney insufficiency. For patients who are old and weak, with serious insufficiency of heart, liver and kidney functions, bone marrow dysfunction, other complications and tendency of infection and bleeding, chemotherapy is not suitable. For lung cancer, chemotherapy and radiotherapy are mostly used in combination in clinical practice. If lung cancer is diagnosed, one should go to hospital in time and actively cooperate with doctor’s treatment plan. Lung cancer patients can reduce the adverse effects of the disease through “early detection, early diagnosis and early treatment”, and many of them may survive for a long time, so it is suggested that patients should establish confidence in treatment.