A fiber-optic temperature sensor based on fluorescence intensity ratiometric (FIR) method is proposed and investigated experimentally. Plastic optical fibers are employed for transmitting the excitation light and collecting the Rhodamine B (RHB) and Rhodamine110 (RH110) fluorescence signals. Given that the fluorescence intensity of RHB is temperature-dependent while that of RH110 is temperature-independent, the temperature can be measured by calculating the fluorescence intensity ratio of these two dyes. To achieve a desired performance, the optimal integration ranges of fluorescence intensities of the two dyes are identified via considerable experimental tests. Indeed, a precise measurement is achieved in experiments. The feasible range of temperatures is from 25 ℃ to 60 ℃ ; a minimum rms temperature error of 0.38 ℃ and a sensitivity of 0.0134 /℃ are achieved. Further, the proposed sensor is proved to be insensitive to fiber bending for bend radii exceeding 9 mm. Thus, the sensor can be used for in situ temperature monitoring.