Abstract: We introduce the mechanical mechanism and parameter determination method of hydraulic fracturing. Based on actual production conditions of Tongxin Mine, we determine the parameters of special thick hard roof, including fracturing points position, water injection pressure, injection rate, injection time and the drilling angle, and design drilling layout program. The practice of 8105 working face in Tongxin Mine shows that the periodic weighting step distance of working face reduces 4.6 m by using hydraulic fracturing and the support resistance decreases 8.8%, which makes a good application effect.