Abstract: Combined with the measured data of the observation line above the 8104 face and its geological and mining conditions, the surface cracks development process mechanism were revealed. The reason that it did not cause obvious surface cracks above the lower gateway of the 8104 face was pointed out that the pillar between the 8104 and the 8103 face was crushed. The development cycle of the trend surface cracks and the cycle breaking distance of the immediate roof is basically the same. Surface cracks development were more obvious in the compression deformation zone near the tendency observation line above the upper gateway. The distinctive feature of the overlying rock of the 8104 face is characterized by bedrock thick and loose layer thin, which show that the thick hard rock could strongly weaken the mining-induced stress and strain transfer and effectively slow down the release of stress and strain, and then slow down the dramatic surface cracks occur. According to the geological and mining conditions in the mine for production and life of the mine people, the major hazards of surface cracks were analyzed, there are easy to derive geological disaster and pose a threat to mine safety in production and endanger mine ecological environment.

Key words: mining subsidence, surface cracks, formation mechanism, hazardous