Background: Deoxynivalenol (DON) is a type B trichothecene that occurs predominantly in grains such as wheat, maize, and barley and has been implicated in incidents of mycotoxicoses in both humans and farm animals. Objective: In the present study, we chose 60Co γ-ray irradiation to degrade DON. Methods: First, the degradation effect of irradiation on DON was analyzed. Second, the toxicity analyses of radiolysis products were studied by oral gavage. Results: The results indicated that 60Co γ-ray irradiation had significant degradation effect on pure DON: when 20 kGy γ-ray irradiation was used for 2 μg/mL DON in acetonitrile-water, the degradation efficiency of DON was 83%, and 2 μg/mL DON in ultra-pure water was completely degraded after 5 kGy γ-ray irradiation. The concentration of 200 μg/mL DON in ultra-pure water had significant toxicity to mice: decreased body weight gain and feed consumption as well as pathological changes in liver and kidney were observed compared with the control group. Conclusions: No significant toxicity was observed in mice that were given these degraded solutions treated by γ-ray irradiation, which indicated that the toxicity of radiolysis products in ultra-pure water had significantly decreased after treatment by γ-ray irradiation. Highlights: This research offered some reference to detoxify DON in cereal grains.