Abstract We investigated changes in the physical and chemical properties of rapeseed straw after treatment with different doses of 60 Co γ-irradiation (0 kGy-1200 kGy). Raman spectra, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) analyses of the pretreated samples showed that the irradiation partially destroyed the intra- or intermolecular structure of rapeseed straw. Particle size distribution and specific surface area analyses suggested that irradiation decreased the particle size, narrowed the distribution range, and increased the specific surface area. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) curves showed that increasing the irradiated dose decreased the thermal stability of the treated rapeseed straw and increased the reactivity. Elemental analyses suggested that the oxygen content slightly increased, suggesting that oxygen in the air may be involved in the reaction. These results demonstrate that γ-irradiation can induce a series of changes in the physical and chemical properties of rapeseed straw.