The MOSFETs are built on SIMOX material, the oxide positive charge, interface state, threshold voltage and leakage current of MOSFETs/SOI after ⁶⁰Co-γ irradiation are measured with I-V technique. The results indicate that the accumulation rate of oxide charge density is more than that of interface state density in dose range of 0-3×10⁴Gy (Si), and the "on" radiation bias is worst case for NMOSFET and PMOSFET.