The stopping power and accumulation energy for protons in SiO2 are calculated by using Monte Carlo software TRIM95. As a result, the ionizing stopping power and the nucleus stopping power are compared for protons in SiO2, and the relation between absorption dose of material surface and factual absorption dose of sensitive area is discussed. CC4007RH and CC4011 devices were irradiated with Co-60 gamma rays, 1MeV electrons and 1—9MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. The result show that the radiation damages from Co-60 gamma rays, 1MeV electrons and 1—7MeV protons were equivalent for 0V gate bias conditions. Under 5V gate bias, the radiation damage for Co-60 gamma rays was most serious. The distinction in damage between 1MeV electrons and Co-60 gamma rays was not large. The damage from protons below 9MeV was always less than that from Co-60. The lower the proton energy, the less the damage.