Response of PMOS dosimeter to total dose has been studied under ionizingradiation with 60Co γ-rays. The results showed that there was an obviousdependence of △ VT on dose rate. By means of I- V subthreshold curve measurementthe contribution of irradiation induced interface state positive charge to the dose rateeffects was found and the relationship of total threshold voltage shift △ VT and dosewas KDn. The power n decreased with increasing dose rate.