In this paper an analysis of optical filter based on fiber-optic ring resonator using polarization and birefringence effects in the resonator loop is presented. The temperature variations, which affect the refractive index and radius of the ring, would cause a change in the filter response. The simulation results show that the resonant wavelengths would shift toward longer wavelengths and output intensity changes with increasing temperature. It is shown that for every 10 deg C change in temperature, would cause the resonance wavelength to increase by 0.1 .