Abstract: Based on the data and information derived from gravity and magnetic investigations in the South Jiangsu with computer processings and combined with relative geological studies, it is suggest ed that the characteristics of the gravity and magnetic fields and the upper crustal layered structures show as follows: 1. A series of interval positive and negative abnormal zones of gravity and magnetic fields, ab normal gravity and magnetic gradients distributed along various trends,and abrupt changing and contortion of axial abnormalies have suggested that a number of NE, NNE composite anticline and syn cline-folding belts and NE, near-NW, NNE and NW four groups of structures formed in the various periods have developed in the area of the South Jiangsu. 2. the distribution of gravity and magnetic field intensity and their physical characteristics re veal that the overthrust in various trends and regional decollements developed in different levels and depths accompanied with foldings and fault structures in the area. 3. The upper crust of the area is characterized by three layered structures i. e. the layer of basement structures, the layer of petroliferous structures and the layer of draping structures.