Abstract: In this paper, the characteristics of the deep erustal structures in South Hebei province and its adjacent area and its relationship to the strong earthquakes were sfudied by the use of the regional gravity data, e. g. the Bouguer Anomaly, Map (1:1000000) and the geological information. The main method used are: 1). utilizing 3-D normal gravitional calculation to remove the influence resulted from the shallow crust layer by layer, a series of the residual gravity anomalies and the deep residual gravity anomalies were tained. The authors had made the analysis for the trend of some active faults and structures in the different depth based upon the transform of the anomalies patterns. 2). Thedepth of Moho surface was inversed and the map of the crustal thickness of the whole region was obtained. The deep crustal tectonic back-ground of the strong earthquake area was analysed and studied on the basis of the above results. The region which should be observed by some precursory methods were finally outlined. This may have interest with the study of seismogeology and the seismic intensity zonation.