When patients with lung cancer have dyspnea after radiotherapy, first of all, the cause of dyspnea should be identified, such as whether the dyspnea is caused by tumor progression, pneumonia, pericardial effusion, pleural fluid, or anemia or other systemic causes. The most common cause is pulmonary infection. If pulmonary infection is confirmed by blood, imaging and calcitoninogen, then bacteriological culture can be used to find sensitive antibiotics and anti-infective treatment can usually be effectively controlled. If bacterial, fungal or viral infection is ruled out and it is radiation pneumonia, if this is the case, mild to moderate treatment is systematically planned by glucocorticoids. Most patients can also be effectively controlled. If there is a combination of malignant pleural effusion and pericardial effusion, dyspnea caused by this condition, radiotherapy may have to be stopped. Then do the appropriate symptomatic treatment for pleural effusion and pericardial effusion, and if it is anemia or other causes, then do the symptomatic treatment according to the causes.