Abstract: The effect of total irradiation dose on the hysteresis loops and C-V characteristics of PZT ferroelectric capacitors was investigated. It shows that, with the increase of the γ dose, the remanent polarization and coercive fields of the PZT capacitors increased while the dielectric constant decreased because of the effects of radiation-induced defects. According to these results and radiation theory about ferroelectric materials, a defects model was proposed to interpret the variation of remanent polarization during irradiation.