The model of interface traps and body defects caused by radiation ionization damage in oxides in semiconductor devices is studied. Using the Backward Euler method to deal with the time discretion and using the linearity method to deal with the nonlinear drift-diffusion reaction equation, the numerical simulation of the interface traps and body traps generated by the silica layer in the Metal–Insulator–Semiconductor(MIS) structure is completed. The algorithm is implemented on the high-performance parallel finite element software―Parallel Hierarchical Grid(PHG). The numerical results of the simulation are consistent with the Enhanced Low Dose Rate Sensitivity(ELDRS) in the ionization damage experiment and the data under different hydrogen ambient conditions. The corresponding models are analyzed aiming for the simulation results.