Abstract: The locations of fire sources in small coal mines are concealed and difficult to accurately identify. A single detection method for concealed fire sources from coal spontaneous combustion makes it difficult to accurately determine their locations, and the concealed fire sources cannot be effectively extinguished. To address these issues, the southern mining area of the Xiaoyao Coal Mine in Inner Mongolia was selected as the case study and proposed a combined detection method using self-potential and radon measurement method to detect concealed fire sources. The area with abnormal self-potential was delineated using the self-potential method, and the area with high radon concentration levels was delineated using the radon measurement method. The spatial distribution characteristics of the detection results from the two methods were comprehensively analyzed to determine the spatial location and distribution range of the concealed fire sources. Based on the self-potential and radon concentration detection results, the high-temperature combustion area, temperature-rise development area, strong interference area, and normal area were comprehensively interpreted and delineated. The overlapping area of self-potential anomaly and radon concentration anomaly was defined as the high-temperature combustion area. The non-overlapping area of the self-potential anomaly was defined as the temperature-rise development area or strong interference area. The non-overlapping area of the radon concentration anomaly was defined as the strong interference area or normal area. For the detected fire source areas, curtain grouting technology was used to treat the concealed fire zones. Curtain holes were arranged along the fire zone boundary, and a mixture of cement and water glass was injected to form a continuous sealed isolation belt to block air leakage. Boreholes were drilled in the center of the fire zone, and fly ash and slurry were injected for fire extinguishing. The results showed that after grouting treatment, the temperature and CO concentration in the goaf decreased significantly, achieving efficient control of the concealed fire sources.