Radiation responses and variation characteristics of PNP input bipolar operational amplifier LM837 have been studied in two different radiation environments under the 1MeV electron and 60Coγ irradiation. The parametric failure mechanism of LM837 caused by a total dose radiation for different biases has been discussed through analyzing the characteristics of LM837 which is annealed at room temperature, 100 ℃ and 125 ℃ after irradiation. The results show that the ionization damage is the primary damage for LM837 caused by 1MeV electron irradiation, and it is larger than that by 60Coγ source irradiation under forward bias condition. In the different radiation environments, bias current under forward bias condition changes larger than that with zero bias. Annealing characteristics of LM837 after irradiation are dependeut on the annealing temperatures, and this relationship is directly related to the increase of radiation-induced interface traps during irradiation.