Abstract: The effects of hydrogen/electron dual-beam irradiation on the microstructure damage behavior of a new 12Cr-ODS ferrite steel made by chemical socking method was studied in this work. The results show that, at the beginning of irradiation, the dislocation networks remain in the matrix owing to the pinning of oxides; as dose increases, defect clusters start to form on/around the dislocations, their number densities get higher and sizes become lager, then the defect clusters turn into interstitial dislocation loops; the voids can form at different temperatures with high number density and small size; also with the increasing of dose, the coarsening rates of the voids slow down, and the number densities of the voids decrease slightly; with a dose of 15 dpa, all the void swellings are 0.15% smaller even at different temperatures. The 12Cr-ODS ferrite steel shows a good resistance to irradiation during the dual-beam irradiations over 623-823 K.