Abstract: The Pseudo-MOS transistors and nMOS transistors were fabricated in SIMOX（Separation by Implanted Oxygen）SOI（Silicon-on-insulator）wafers unhardened or hardened by silicon ion implantation. The total dose response of transistors mentioned above was investigated under 10 Kev X ray radiation. The results show that the hardening procedure is a very effective method to enhance the hardness of the SIMOX SOI materials and that the Pseudo-MOS transistor can be used effectively to replace the nMOS transistor in evaluating the resistant ability of SOI materials to total dose radiation.