Radiation effects and annealing characteristics are investigated for different types of operational amplifiers at four dose rates ranging from 100 to 0.01 rad(Si)/s for same total doses. The results show that for the bipolar op-amps, the degradation is more pronounced at low dose rate than at high dose rate and dose rate effects also exist for CMOS op-amps, but different from bipolar op-amps. It represented that the lower the radiation dose rate was applied, the less the devices were damaged, and the deference induced by high dose rate irradiation can be eliminated by a long time annealing in room temperature. JFET-Bi op-amps have not only enhanced low dose rate sensitivity (ELDRS) effects when irradiated but also further obvious effects of post-radiation damage when annealing at room temperature. Moreover, it is also found that there is no difference when the pMOS-Bi op-amps was radiated in different dose rates.