The accurate detection of coal mine fire source and goaf location is of great significance to coal mine safety management. The basic principle of detecting fire source and goaf location by radon measuring method was briefly analyzed, and the composition and performance of the radon monitor by electrostatic collection method were studied. The results show that the location and range of fire source and goaf can be determined through detecting the high concentration area of radon by with isotope radon measurement method, which provides a scientific basis for subsequent drilling grouting. The radon monitor based on electrostatic collection method can eliminate the influence on the detection results by energy spectrum screening, the detection performance of the radon monitor can be improved through improving the electric field strength, reducing the air humidity and increasing the volume of the collection chamber, which provides theoretical support for the structural design and optimization of the radon monitor.