Abstract: In the water discharge trial in Xingtai coal mine,the variation laws of the environmental isotopes T,D and ¹⁸O in the water are revealed.According to the laws,the degree"Daqing" aquifer affected by Ordovician Karst aquifer and the possible recharge source of"Daqing" aquifer are analysed and discussed,and the minefield can be divided into three hydrogeologic units which are different in the source and the intensity of rechargeOf underground water. The study of the isotopes indicates that this mine field is one of fault block karst waterarea whose north side is the only location that underground water inrushes but the other three sides are difficultfor water inrush.This result will be very imPOrtant to harnessing and preventing mine water in the mine field.