Total-dose irradiation responses of HfON and HfO2 dielectric films were studied with their MIS structures and under 10keV X-rays. The flatband voltage shifts of HfON MIS structures are much smaller than HfO2 MIS structures under different total-doses up to 30 kGy(Si). The influence of the added nitrogen element on total-dose irradiation tolerance of Hf-based dielectric films was also discussed.