Abstract: Aiming at the serious rib spalling problem of the full-mechanized mining of coal seams in the water- bearing thick coal seam in Kejiagai Coal Mine, the characteristics of the coal wall slice, the mechanism and effect of the deep-hole micro-blasting were studied by field measurement, theoretical analysis and numerical simulation. The results show that the coal seam wall cracks developed vertically after drought water, which makes the coal seam slide laterally in the middle and upper part of the working face; the deep-hole micro-blasting promotes the interlocking of the fracture network in the coal body and enhances the friction between the divided coal blocks. With the cohesive force, it effectively controls the coal wall framing; puts forward and implements the deep-hole micro-blasting technical measures for the large mining height of coal seam with watery thick coal seam, and studies the micro blasting technology, drilling arrangement and installation drug parameters. After the implementation, the maximum rib height of the coal wall is 2.6m, the maximum rib depth is 0.8m, and the width of the ribs is 2.9m. The coal wall rib spalling is effectively controlled.