The dielectric properties of epoxy-silicone resin coatings containing carbon black (CB) and carbonyl iron (CI) particles as a function of frequency (2-18 GHz) and the CB volume content (0.2-1%) have been investigated. The complex permittivity of the coatings increased with increasing CB content, which mainly attributed to the interfacial polarization at the CB/resin/CI particles interfaces. The complex permittivity also decreased rapidly with increasing frequency in the low frequency range while decreased slowly in the high frequency range. The changes of dielectric properties with frequency and the CB volume content were discussed using the power-law decay and the concept of interfacial polarization.