Abstract: During the procedure of radiotherapy, parts of normal lung tissue will be exposed inevitably, which can cause acute and chronic radiation-induced lung injure (irradiation-induced pneumonia and irradiation-induced pulmonary fibrosis). Radiation-induced lung injure effect quality of life of the patient deeply and the lung is the major dose-limiting organ for radiotherapy of cancer in the thoracic region. Therefore, it is very important to research the pathogenesis of radiation-induced lung injure, which can give us some directions to prevent and/or treat irradiation-induced pulmonary damage.