In this paper, the silicone rubber composed of carbon fibers was prepared. The influence of different concentration of carbon fibers on the conductivity, electromagnetic shielding interference effectiveness property of the silicone rubber was discussed from the point of view of condition of carbon fiber and silicone rubber. The results showed that there existed the extreme conductivity and shielding effectiveness (SE) across the tested frequency range from 2.6 GHz to 3.95 GHz of silicone rubber composites filled with carbon fibers. When the content of the carbon fibbers was 50 parts per hundred of rubber (phr), the SE values of composites were typically above 63 dB and close to the extremum. The compact packing structure of carbon fibers does not play an important role in improved the conductivity of composite. The SE of the composite depends on the conductivity of composite.