Abstract: In this paper, For example Xinjiang Xiaodonggou coal mines, To andyze: When coalfield fire is extinguished the fire zone like a catchment since ground subsidence there for collecting the precipitation. Therefore, the pyrite embedded in the coal seams is going to oxidized to generate sulfate which leads the seams continue to oxidize. The mechanism of such oxidization, its characteristics and generative conditions are significant for the detection and control of coalfield fire and its related environmental issues.