Abstract: In order to design and manufacture a new type of phase retarder, a multi-period binary 1-D photonic crystal composed of zinc sulfide (ZnS) and cryolite (Na₃AlF₆) was prepared on the glass with a refractive index of 1.52 by using the characteristic 1-D photonic crystal. Numerical simulation calculation and theoretical analysis were carried out. The analysis results show that, the effective refractive index of one-dimensional photonic crystal is the virtual equivalent refractive index in the band gap range. At oblique incidence, the phase of the reflected light of the p light and s light in the band gap increases, the phase delay occurs, and the polarization state changes from linear polarized light to elliptical (circular) polarized light. When total reflection occurs, the effective refractive index of the optical sparse medium is the virtual equivalent refractive index. The phase of reflected light increases and phase delay is observed at the same time. Its polarization state changes from linear polarized light to elliptical (circular) polarized light. The propagation direction of light and the phase of polarization state can be changed by using the retarder, and the defect of thin film λ/4 wave-plate is solved.