Abstract: The room mining goaf of 4^# coal seam over 5103 fully mechanized working face which belongs to Chengyi Coal Mine of Inner Mongolia Yitai Coal Company has been a fire zone. Therefore, through monitoring the fire zone by drillings, we calculated the height of caving zone and fault zone of 5^# coal seam, and proved a conclusion that the coal mining of 5^# coal seam would not be affected by burning flame. However, the poisonous and harmful gas may invade the working face to cause damage. So, we decided to use pressure balancing ventilation technology in 5103 working face. Through supercharging pressure and regulating pressure experiment, we have found this technology can not only wipe out the threats which come from the fire zone, but also complete mining of 5103 working face safely.