To shield the detection radar wave for radar/infrared combined guidance weapons, an idea of designing a kind of combining frequency selective surface (FSS) coatings is proposed on ZnS substrate. The coatings are not only infrared transparent, but also have bandpass properties in radar wave band. An inductive mesh which is treated as the initial structure is designed and analyzed. An FSS structure with aperture element of cross shape is designed and analyzed by a socalled Galerkin′s method in the spectral domain. The resonance frequency of this FSS structure is 31.75 GHz, whose transmittance is about -0.38 dB. The resonance frequency of FSS on perfect conductor (PEC) surface which has the same parameters is 33 GHz. Antireflection coatings are designed by optical coatings theory with two coating materials to improve the infrared transmittance of this combination structure. The total layers′ thickness is 1.085 μm. The sample is fabricated by depositing coatings and lithography. The test results indicate that the transmittance at radar central resonant frequency of 31.5 GHz is about -0.63 dB, and the average transmittance (out of central frequency) is lower than -7.51 dB . The average transmittance is 87.95% in longwave infrared region.