Abstract: The thermodynamic parameters of surrounding rock of the coal seam in a certain gasification field in Inner Mongolia are measured,and the relationships of the heat capacity and thermal conductivity of the surrounding rock of the coal seam and the temperature were established.COMSOL Multiphysics was used to simulate the temperature field of overlying strata in this study area.According to the temperature field,the FLAC^3D model was established,the temperature was applied in the overlying strata by adjusting the mechanical parameters of mudstone,and obtained the gasification strata fissures characteristics in the study area.Compared the actual value of fissure height with the value of simulation,in the 5% confidence interval,R² is 0.91,the rationality of the mechanics model was verified.