Based on the analysis of the mechanism of irradiation damage and total dose effect on Schottky barrier diodes (SBD), using the model of the carrier mobility fluctuation and carrier number fluctuation of 1/f noise, the effect of irradiation damage on 1/f noise of SBD was studied in this paper. The research shows that, the irradiation induced interface states change the distributing of interface state density, and, moreover, modulate the Schottky barrier height and increase the velocity of recombination in the surface, leading to the degradation of device performance as well as the significant increasing of 1/f noise level. So, 1/f noise is closely related to SBD's degradation, namely, the larger the magnitude of 1/f noise and the deviation from standard value, the worse the reliability of device, and it's also an indicator of bad radiation-proof performance, which causes its high failure rate in radiation environment. Thus the 1/f noise acts as a researching tool on the mechanism of irradiation damage of SBD, also provides the theoretical basis for nondestructive irradiation hardness assessment.