In order to expand the characterizationscope of high-level radioactive geological disposal buffer materials, and clarify the effects of gamma irradiation and thermal aging on radicals in Gaomiaozi natural sodium bentonite, the changes of free radical concentration, functional group, the state and content of Fe were analyzed using electron spin resonance spectrometer, fourier transform infrared spectrometer and Mossbauer spectrometerunder different γ-rays irradiation dose(500 kGy, 100 0 kGy, 150 0 kGy, 200 0 kGy, 250 0 kGy and 300 0 kGy), aging temperature(90 ℃ ,150 ℃ ,170 ℃ , 190 ℃ and 210 ℃), aging time(2 monthes , 4 monthes , 6 monthes , 8 monthes , 10 monthes and 12 monthes) taking Gaomiaozi natural sodium bentonite in Inner Mongolia and Beishan groundwater as research objects. Addtionally, these four parameters were analyzed under different aging temperature(90 ℃ ,150 ℃ ,170 ℃ , 190 ℃ and 210 ℃) and aging time(2 monthes , 4 monthes , 6 monthes , 8 monthes , 10 monthes and 12 monthes) with the accumulative radiation doses of 300 0 kGy.The preliminary analysis of mechanism was also discussed. The results indicat that the content of radicals first increased and then decreased with the accumulative irradiation dose, thermal aging time and temperature increasing. There was a significant superimposed effect of irradiation and aging. During the aging process, Fe(Ⅱ) was transformed to Fe(Ⅲ), and this transition could activate O2 to ?OH under dark conditions, the formation trend of ?OH was consistent with the oxidation of Fe(II). The effect of ?OH content in bentonite by Fe(II) activation was very important under above condition, and further research of which was recommended.