The change of electrical performances of silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) andSi bipolar junction transistor (BJT) was studied as a fumction of reactor fast neutron radiation fluence. After neutron irradia-tion, the collector current Ic and the current gain β decrease, and the base current Ib increases generally for SiGe HBT. Thehigher the neuron irradiation fluence is, the larger Ib increases. For conventional Si BJT, Ic and Ib increase as wellas β decreases much larger than SiGe HBT at the same fluence. It is shown that SiGe HBT has a larger anti-radiationthreshold and better anti-radiation perrormance than Si BJT. The mechanism of performance changes induced by irradiationwas preliminarily discussed.