In this experiment, rapeseed straw was used as material, six irradiation doses of 60Co–γ(0, 400, 600, 800, 1 000, 1 200 kGy) were designed to analyse the degradation products of cellulose, hemicellulose and lignin by GC–MS. The results showed that the degradation rates of cellulose, hemicellulose and lignin were all improved in different degrees with the increasing of dose. With the dose of 1 200 kGy, the degradation of cellulose, hemicellulose and lignin was 69.06%, 42.57% and 4.99%, respectively. 22 fatty acids, 5 aromatics and no furans were detected from the water extracts of untreated straws, while 25 fatty acids,17 aromatics and 5 furans were detected from the water extracts of treated straws. The variety and content of the products showed different with different dose treatment.