An optical fiber temperature sensor using two fluorescent dyes based on Fluorescence Intensity Ratiometric (FIR) method was proposed. In experiment, Rhodamine B and Rhodamine 110, which were temperature-sensitive and temperature-insensitive respectively, acted as the sensing materials. Polymer optical fibers were utilized to transmit excitation light and collect emitted fluorescence. The two dyes- fluorescence spectra could be separated conveniently since their respective emission peaks were 60 nm apart. The optimal spectral intervals of RH110 and RHB for FIR were identified. By calculating the fluorescence intensity ratio of the two dyes, the calibration curves of intensities ratios vs temperature were obtained with good linearity. The effects of different concentrations of fluorophore on the calibration curves were also studied. When the concentrations of dyes were 0.3 g/L, a minimum rms temperature error of 0.28℃ and a sensitivity of 0.0128/℃ were achieved. Moreover, the influences of illumination source-s fluctuations and dyes- photo-bleaching can be eliminated to some degree.