Ni/4H-SiC Schottky barrier diodes （SBDs） were fabricated, and irradiated with the 60Co gamma-ray source to the accumulated dose of 1 Mrad（Si）. The 0 V and -30 V bias voltage were applied to the SBDs during irradiation. After 1Mrad（Si） radiation, the Schottky barrier height and ideality factor of the Ni/4H-SiC SBDs under different bias voltages basically remain at the same values, and the minority carrier lifetime of the epitaxial layer also has no degradation. The reverse current decreases after radiation, which can be explained by the negative surface charge increase. The results show radiation bias voltage has no obvious influence on the radiation effect of the Ni/4H-SiC SBD.