According to the geological，mining，ventilation and prevention factors of spontaneous combustion in coal seam, Analytic hierarchy process(AHP) and fuzzy comprehensive evaluation were used to set up comprehensive evaluation structure, the corresponding values of non spontaneous combustion seam，spontaneous combustion seam，spontaneous combustion coal seam and easily spontaneous combustion coal seam were respectively 0.661-0.804，0.447-0.661，0.269
-0.447，0.162-0.269. The risk of spontaneous combustion is quantified in coal seam. The influence of subjective factors can be effectively reduced by this evaluation system，and the results were more accurate. The technology provides a way to evaluate the risk of spontaneous combustion in coal seam.