Abstract: Grouting reform is one of effective technologies for water prevention and control in mining lower coal seams in north China coal mines.But this technology can only be applied in mining shallow lower coal seams at present, with the mining depth increase, grouting reform for thin limestone aquifer under coal seam floor can not meet the conditions for safe mining.With mining lower coal seam No.9 in Dongpang mine for example, water-rich characteristics and grouting reform technology of karst aquifer in Ordovician Fengfeng Formation have been detailed and discussed in this paper, the conclusions show that grouting reform for the upper part of Ordovician limestone in Dongpang mine is technically feasible, the thickness of grouting reform is 40m.Grouting tests showed:74 percent of water amount was reduced, grouting result was good, and next work proposals of water prevention and control were put foward.