In order to study the radiation reliability of polysilicon emitter bipolar transistors, the high dose rate irradiation test and room temperature annealing test of ⁶⁰Co γ ray in the polysilicon emitter NPN transistors were performed under different bias conditions. The experimental results showed that the base current IB increased significantly after radiation, and the collector current IC did not change much. The radiation damage of IB was more serious under the reverse bias condition. After annealing at room temperature, IB had a certain degree of sustained damage. The contrast test results showed that radiation reliability of the polysilicon emitter NPN transistors was better than that of crystalline silicon emitter NPN transistors. The radiation damage mechanism of the polysilicon emitter NPN transistors was analyzed based on device structure and process condition, and the difference of radiation damage between polysilicon and crystalline silicon emitter NPN transistors was analyzed.