Abstract: Abstract：Taking 42204 working face of bultai coal mine as the engineering background，using theoretical analysis and field test, the mechanism of abnormal ground pressure and application of prevention technology during the working face passes through the coal pillars are studyed. The results show that: The theoretical minimum mining height without instability of the roof of the overlying working face is 10.32m, Through theoretical calculation, the minimum collapse height required to fill the goaf is 31m, Combined with the occurrence characteristics of rock stratum, the reasonable fracturing horizon is calculated, The hydraulic fracturing scheme of "directional long drilling in working face + along slot shallow hole" is put forward. The results of ground pressure monitoring data show that the length of periodic pressure on the roof decreases, The goaf can be enriched by caving roof rock blocks, the maximum subsidence of the roof in the triangle area of the tail of the working face is 200mm, The maximum subsidence of the roof of the return air roadway is 80mm,The maximum approach of two sides is 150mm, The application results show that hydraulic fracturing can weaken the integrity of the roof, The ground pressure of working face in the area affected by coal pillar is reduced.