Abstract: In this paper, the ionizing damage effects and annealing behavior of foreign manufacturer production PMOSFET in 4007 circuit under different dose rates and bias conditions were investigated. The experiment results show that the PMOSFETs threshold voltage negative shift is more obvious with the dose rate reduction. It is thought that the PMOSFET of this kind of type has enhanced low dose rate sensitivity (ELDRS) effect. The PMOSFETs threshold voltage does not recover at room annealing after high dose rate exposure and continues the negative drifting, which is due to the radiation-induced interface traps build-up. The annealing temperature is higher, the threshold voltage return drift is more obvious. Zero bias is the worst bias condition.