The effects of the birefringent wedges in the cross-correlation polarization demodulation system of optical fiber Fabry-Pérot sensors are analyzed.A mathematical model for the optical path difference is established based on the results of the incident angle,optical axis and oblique of the wedge surface.The error of the optical path difference between the theoretical model and the simple model is simulated.The analysis results indicate that the error of the simple model for optical wedges is less than 15 nm only if the incident angle is less than 0.3°,and the optical axis is less than 0.8°and the vertical error of the wedge surface is less than 0.15°,when the wedge angle is 4°.The fringes of the experiment based on polarized light interference with the birefringent wedge are mostly consistent with the theoretical fringes.The slope difference between the experimental fringes and the theoretical fringes is 0.02°.