In this paper, the effects of 2 MeV electron radiation on parameters h,FE, t,off, and C,T, of silicon bipolar transistors is reported. The changes of these parameters depended largely on characteristic of defect level in transistors introducced by electron radiation. The measurement results indicate that reduction of minority carrier lifetime and effect of majority carrier removing induced by these defects level are direct reason for changes of h,FE, t,off, and C,T,.