Abstract: In order to strengthen the prevention of spontaneous combustion in goaf of coal mine, a new optical fiber sensing temperature measurement technology was proposed to accurately determine the high temperature area of goaf in this paper. Through laboratory tests, the temperature precision, positioning accuracy and response time of the optical fiber temperature measuring device were measured, the arrangement means of optical fiber in goaf interior were also described. The reliability of optical fiber temperature measurement was discussed by comparing the optical fiber temperature measurement results with the beam tube monitoring results. The distribution of "three zones" of spontaneous combustion in goaf is as follows: the scattered tropical zone is within 35 m, the spontaneous combustion zone is between 35 m and 110 m, the spontaneous combustion zone on the side of the transport gateway extends to 120 m, and the suffocation zone is 110 m away, which is basically consistent with the beam tube monitoring data; the high temperature area inside the goaf appears within 80 m to 100 m from the working face, the high temperature point appears in the goaf 100 m away from the working face and 50 m away from the transport gateway. The fiber optic temperature measurement system is used as the effective basis for determining the risk area of spontaneous combustion in goaf, and also can be used to locate the high temperature area.