BaF2-TiO2 nanocomposite material (hereinafter called the composite) was prepared by a sol–gel method. And the composite surface area, morphology and structure were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction(XRD) and scanning electron microscopy (SEM). The results showed that BaF2 and TiO2 form a PN-like structure on the surface of the composite. Composites were used to catalyze the degradation of methyl orange by irradiation with ultraviolet light, γ-rays, and an electron beam(EB). It was demonstrated that the composite is found to be more efficient than prepared TiO2 and commercial P25 in the degradation of methyl orange under γ-irradiation. And increasing the composite catalyst concentration within a certain range can effectively improve the decolorization rate of the methyl orange solution. However, when the composite material is used to catalyze the degradation of organic matter in the presence of ultraviolet light or 10 MeV electron beam irradiation, the catalytic effect is poor or substantially ineffective. In addition, a hybrid mechanism is proposed; BaF2 absorbs γ-rays to generate radioluminescence(RL) and further excites TiO2 to generate photo-charges. And due to the heterojunction effect, the resulting photo-charge will produce more active particles. This seems to be a possible mechanism to explain γ-irradiation catalytic behavior.