Abstract: In recognizing seismic precursory anomaly of groundwater regime, we must analyze the characteristics of groundwater regime in many years, disturbering factors on water level and the relationship between the anomalous variation and seismic activity based on geological and hydrogeological condition of observational wells.In this papar, throuth above analysis, it is considered that there were anamalous variations in water lever in three wells at Wanquan, Xongxian and Wanxian of the groundwater observational network of Hebei provnce prior to the Datong 6.1 earthquake.