Abstract: Abstract: Aiming at the difficulty of roof caving for the first time in the process of cutting advancing 15209 working face of zhangjiamao coal mine, field measurement, theoretical analysis and three dimensional hole model analysis were carried out, combined with the fact that the joints and cracks in the roof of the 5-2 coal seam are not developed, the coal seam on the working face is unstable and sandwiched with gangue, the water pressure cracking scheme of the roof is determined to ensure the stability of the coal wall and the top of the two roadway. For this reason, the roof is cracked by using water pressure to optimize the hole layout in three-dimensional space and through the cracks between the boreholes. According to the on-line monitoring of working face roof pressure and the field measured data analysis of coal wall and two sides deformation, the scheme has a good application effect.