Abstract: In order to achieve the measurement of temperature in harsh environments,a fiber temperature sensor system based on the fluorescent lifetime was designed. 415 nm LED was selected as the light source and a rare earth material Y₂O₂S:Eu was selected as the sensitive material. Finally,the fluorescence lifetime of sensitive material was measured by a probe amplifier and signal acquisition module and temperature measurements were realized due to the monotonic relationship between the fluorescence lifetime and temperature. Temperature experiments were carried out using an oil bath heating method, and the experimental results showed that: the temperature measurement can be realized in the range of 25~80 ℃ and the temperature sensor has an average resolution of 0.5 ℃.