Abstract：Some of the water inrush accidents in mining are caused by unfavorable blocking of boreholes；and water inrush caused by unfavorable blocking of boreholes in aquifer of Ordovician limestone is the most harmful. Taking Xinglongzhuang coal mine for example，the potential water leakage of the boreholes in aquifer is introduced according to the hydrogeological data collected from the new water exits in coal crosscut of mining area I in Ordovician limestone. Water samples show that the water is located in Ordovician limestone and abnormal water level in X-down stratum of Ordovician limestone is found；and the potential leakage passage is determined，which may be caused by unfavorable cement blocking of boreholes. Because of the changes of the geological conditions of the boreholes¢ positions，the boreholes may penetrate into the water-enriched area of the Ordovician limestone；and then water drainages toward other aquifers with high pressure and high velocity will be formulated，which are the main factors induced by the unfavorable cement blocking of boreholes with the potential leakage passage. A chemical grouting method is presented；and it is found valuable references can be provided with the method for treating the water inrush hazards.
