Abstract: In order to realize the safe and high-efficient exploitation of gas and reduce the risk of coal and gas outburst in single coal seam,the distribution and evolution law of the damage field was studied by means of damage mechanics.The damage variable correlated with the excavation process was introduced,which was used to describe the distribution characteristics of fractures in rock mass.According to the elastoplastic damage theory,the 3D-finite element program was developed,by which the analysis of mining process of one coal seam was made.The material damage accumulation taken into consideration,the distribution and evolution law of the damage field,volume strain and stress was obtained,which can provide a theoretic reference for the design of gas drainage and improving the efficiency of gas extraction.