Investigations on the damage and degradation mechanisms of epoxy resin under a high-energy irradiation and improvement in its stability in irradiation environments are crucial to expand the application of epoxy resin in numerous fields including the aerospace and nuclear industries. In this study, graphene quantum dots (GQDs) were used as free radical scavengers to slow down the degradation of epoxy resin under a γ-irradiation environment, and the anti-irradiation mechanism of the GQDs on epoxy resin was investigated. The results demonstrated that following irradiation, the mechanical properties of epoxy resin exhibited a reduction of 49%, accompanied by a decrease in glass transition temperature by 4.4 ℃. Similarly, the mechanical properties of graphene quantum dots/epoxy resin (GQDs/EP) composites experienced a decline of 35%, along with a decrease in glass transition temperature by 2.2 ℃. Notably, upon the incorporation of GQDs, the generation of free radicals within irradiated GQDs/EP composites was significantly suppressed compared to pure resin. Furthermore, GQDs nanoparticles enhanced both the mechanical properties and thermal stability of epoxy resin prior to and after irradiation. Therefore, GQDs nanoparticles can be used as free radical scavenger to effectively improve the irradiation stability of epoxy resin. The scavenging mechanisms for free radicals mediated by GQDs is closely associated with sp² carbon domains and surface functional groups. This study provides a novel concept and method to improve the stability of epoxy resin under γ-ray radiation.