The present work intends to discover the influences of Co-60 gamma (gamma) ray-irradiation on frequency-dependent dielectric features of Graphene/Silicon Schottky diode with an insulator layer. Graphene (Gr) nanosheets have been synthesized by chemical vapor deposition (CVD) to build a Gr-based p-type Si Schottky diode. The diode was irradiated at 30 kGy and 60 kGy doses. The study has been performed at 300 K in the voltage range -6 V to +6 V at dark conditions both at 400 kHz low-frequency and 900 kHz high-frequency. The experimental results showed that dielectric features of the structure are dependent on the radiation dose and applied voltage and to be a strong function of frequency.