Due to the influence of fiber loss, the temperature measurement accuracy of long distance fiber is low. In order to improve the long distance optical fiber temperature measurement accuracy, a design scheme of distributed optical fiber temperature measuring system is proposed in this paper. The loss of Raman scattering light is determined through the theoretical analysis, and the fitting model is built based on the test data of room temperature. The loss is separated, and the influence of fiber loss on temperature is eliminated by compensating the fiber loss which improves the accuracy of long distance fiber temperature. The real-time dynamic demodulation of fiber temperature is realized by the reference fiber ring. The fiber ring to be measured is placed in a constant temperature water tank at 50℃, 60℃, 70℃ and 80℃ respectively for experiment, and the experimental data are processed and analyzed.The results show that the temperature measurement accuracy of the system is ±1℃, and the spatial resolution is 2 m.