Using the Bouguer gravity anomaly data with topographic correction, the investigation of deep structure in the piedmont fault zone of Taihang Mountain area is done. Based on the Geosoft software processing platform, we use the GM-SYS gravity inversion module for gravity inversion with the constraint of Deep Seismic Sounding （DSS ） profile results which completed in the last two decades. From the four lines of gravity measurement in Taihang Mountain region, the crustal densit） structure in the piedmont fault zone is gotten and the three-dimensional gravity profiles are drawn by interpolation method. The gravity inversion shows that the Conrad and Moho discontinuities increase northwestward gradually from 18 km and 34 km in the eastern coast plain to 28 km and 43 km in the northwest Taihang Mountain, respectively. Both discontinuities deepens abruptly when crossing NNE-trending Taihang zone, indicating that the piedmont thrust fault of Taihang Mountain could extend deep cutting through the Moho. The sediment thickness is generally less than 3 km in mountainous region, but is much thicker （3 - 10 km） over North China rift basins with variations on a series of second - order NNE depression and upheaval structures. The results are basically concordance with the previous studies in this area.