Objective: To explore the effects of radiation injury on metabolic pathways by detecting the volatileorganiccompounds (VOCs) in exhaled breath of rats with Radiation-induced lunginjury based on GC-MS, and to establish a non-invasive, convenient and rapid method for the diagnosis of radiation injury. Methods: The rat model of radiation lung injury was prepared by gradient dose irradiation with cobalt source. The rats were randomly divided into 4 groups according to the irradiation dose: 0 Gy group, 2 Gy group, 4 Gy group and 6 Gy group. Theexhaled breathwerecollected at 1,3,5,7 days after irradiation and analyzed by gas chromatography-mass spectrometry. The samples were analyzed by PCA and OPLS-DA? to find the differential metabolites of relevant VIP>1, and further explore the potential markers of? Radiation-induced lunginjury. Results: There were significant differences in blood phase indexes, HE stained sections of lung tissue and VOCs in exhaled breath between the blank and irradiation groups. 25 kinds of metabolites were initially screened, among which 5 could be used as combinative? potentialbiomarkers. Conclusion: This study provides a theoretical basis for the respiration of radiation damage and an experimental reference for the establishment of a non-invasive diagnostic method for the detection of radiation damage.