In this paper, influences of the dielectric materials on the transmission properties of frequency selective surface are studied with theoretical calculation and experimental verification. The frequency properties, including resonance frequency, transmission bandwidth, and transmission loss, of the FSS with the skin and core of different dielectric constants, different thickness are discussed. The result shows that raising the thickness of the skin and core layer will make the bandpass position shifts to low frequency, reducing the thickness will make the the bandpass shifts to higher frequency. Raising the dielectric constant of the skin and core layer will make the bandpass position shifts to low frequency, reducing the dielectric constant will make the the bandpass shifts to higher frequency. And the transmission properties of the sample flat, which has the same structure the discussed FSS, are tested. Theoretical analysis and experimental results are in good consistency.