Abstract: In order to prevent the serious problem of mining damage in the mining process of Western shallow buried depth and thin bedrock coal seam,based on 3DEC discrete element software,using numerical simulation method,the variation characteristics of bearing arch before and after roof breaking of coal seam are researched.The results show that a bearing arch structure which can maintain relatively stable is in the overlying strata,the structure can protect the safety of mining space to some extent;bearing arch structure changed dynamically with the working face advancing,when the thin bedrock was completely broke,the pressure bearing arch structure was instability and damaged at the same time,and the gravity created by bedrock layers and quaternary system loose bed all impacted on the support,which easily caused the accident of roof cutting and pressing support,so the enough attention should be taken.