According to the high temperature characteristics of the burning coal seam and the diffusion regularity of radon gas, this paper proposed a new calculation method for the burial depth of the burning coal seam based on radon gas measurement. This method was used in the Wuda working area of Inner Mongolia, and the result is quite consistent with that obtained by the magnetic method, suggesting that this method is reliable. The new method can provide a useful means for extracting more information about the coal fire from the radon measurement.