Abstract: The accurate determination of the original gas pressure in coal seams affects the safety production of mine, and the borehole sealing technology is a key factor which influences the original gas pressure determination. Through analyzing the main advantages and disadvantages and the application condition of the existing borehole sealing technology, the new borehole sealing equipment is designed, including the equipment structure, the sealing materials and the sealing principle, and the sealing under pressure technique is determined. The industrial test shows that the new borehole sealing equipment has advantages of better sealing, high success rate of pressure determination and wide application range compared to the cement mortar hole sealing.