The barometric pressure efficiency and interrelation coefficient of groundwater level in five deep wells are calculated by using high-order difference method and the best interrelation result between them is optimized. The anomalous variations on two curves are obtained before the Heze 5.9 earthquake in 1983 and Lulong 5.3 earthquake in 1982. The result indicats that anomalous information obtained from the method is feasible, and can be used as short -impending anomaly before moderate and strong earthquakes.