According to the actual needs of environmental monitoring about power equipment, the technology of the temperature sensing about fiber sensor array is carried out in this paper. An interferometric sensing probe with polarization-maintaining fiber as the sensing unit is proposed. Firstly, a mathematical analysis model of the sensing system is established, and an interference optical path is constructed to explore the influence of the length of the optical fiber sensor probe and wavelength of light source on the temperature measurement range. Secondly, on the basis, the sensor package based on the capillary glass tube is completed and system prototype is built. Finally, the temperature test experiment and sensor repeatability experiment are carried out. The experimental results show that under the same light source with the same wavelength, the shorter the length of sensing probe, the greater the range of the temperature measurement has, and when the sensing probe is 1cm, the temperature measurement error is about 0.37 ℃, and the accuracy is about 0.3 ℃. This research has reference value for the application of optical fiber temperature sensing technology in power and other industries.