Abstract: In view of the present situation that the water discharging of coal working face gas extraction system is hard, using the principle that the density difference of gas and water is large, and water is easy to fall to the bottom of the container and congregate, and using safety principle of redundancy principle to combine automatic drain device with artificial water discharging organically, gas water separation device under a high negative pressure is developed, which carried on the field test in Zhaozhuang Coal Mine and received the good use effect. The results showed that the high pressure gas water separation device can improve the efficiency of the coal seam gas extraction and ensure safe and efficient production of the working face.