Abstract: This paper studies the risk assessment on an iron goaf by using the geological and hydrological conditions affecting the stability, characteristics parameters of mined-out areas as index set according to the principle of Fuzzy Mathematics. 5 rating scales for assessing the mined-out area's stability in China are applied as evaluation set. The percentage between two factors is determined by comparing the multiple factors. We set up the fuzzy comprehensive evaluation model for the Goaf risk assessment. The stability evaluation between the sublevel 420 to 460 goaf of an iron ore is performed by applying this assessment model. The risk evaluation result is in the relative higher level Ⅱ.