This paper discussed on the partial discharge phenomenon occurs in insulating materials-based silicone rubber. In general, the partial discharges occur due to the presence of additional substances or void in the material. The methods that are used to study partial discharge are offline monitoring, online monitoring, and numerical analysis. The numerical analysis was performed on this silicone rubber compound with the introduction of three identical void with the radius of 1.15 mm. The simulation results show that the pure silicone rubber material experiences the high impact of partial discharge activities compared to the second material; microvaristor filled with silicone rubber.