Abstract: In this paper,the effects and mechanisms of ionizing radiation for semiconductor devices are researched. It's an effective way to meet requirement of improving in radiation hardening by device structure optimizatioa The radiation-harden models of FD- SOI/MOSFET have been built,which are based on the 0.18μm CMOS process. And the radiation effects what work on the MOS structure are simulated by DVINCI.Active-Region- Cutout (ARC) technique with dual gate is developed to modify the transistor.It's proved that this structure obtains higher radiation tolerance.