In order to study the long-term stability, natural Gaomiaozi(GMZ) Ca-bentonite and its modified Na-bentonite samples, which suffered different doses of electron beam irradiation or different temperatures and thermal aging time, were analyzed using thermogravimetry-differential scanning calorimetry(TG-DSC). The results show that variations of the peak temperature and initial temperature induced by high temperature aging are larger than those induced by electron bean irradiation. GMZ Na-bentonite performs better in withstanding the electron bean irradiation and high temperature aging than that of the natural Ca-bentonite. The long-term thermal stability of Na-bentonite is better than that of Ca-bentonite under electron irradiation/high temperature aging.Cited