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The effects of neutron and gamma radiation on shielding materials directly influence the safety of nuclear facilities. In this study, a B4C/epoxy resin shielding material was fabricated. The mechanical properties, fracture microstructural morphology, characteristic groups, and thermal degradation of the shielding material under two different irradiation conditions, 1 MGy gamma and superimposed 1.19×1015 cm-2 neutron radiation, were compared. After gamma irradiation for 11.6 d and superimposed neutron irradiation for 3 h, the mechanical properties of the shielding material continued to decrease; however, they did not decrease to 50% of those before irradiation, and radiation degradation occurred instead of material failure. Compared with separate gamma irradiation, the peak intensity in the 1H-NMR spectra of the shielding material near δ=7 did not change significantly after the additional neutron irradiation, indicating that there was no further degradation of the C‒H bond on the benzene ring. At 50% loss in mass, the temperature decreased from 526.3 °C before irradiation to 453.2 °C after gamma irradiation and 463.9 °C after gamma superimposed neutron irradiation, demonstrating the decrease in thermal stability.