The gravity field of South China is obviously different from that of Nor-th China in that the former is characterized by extremely intense negativeanomalies caused by reduction of the density of the lithosphere as a result ofgranitization of the crust. In coastal areas, the Bouguer gravity anomalies showno correlation with the relief of the Moho, and the inhomogenity of densityof the crust and upper mantle seems to play a dominant role in the distribu-tion of the gravity field. The widespread granitoids in South China reflect aspecial crusta' structure of that region. The exposed areas of granites coincidequite intimately with gravity contours, which makes up a favourable prere-quisite for applying gravity data to the quantitative inference and interpre-tation of the shape of granite body at depth. In this paper, a discussion ismade concerning the application of gravity modelling to the study of the earthcrust, the structure of the upper mantle and the subsurface shape of granitesin South China, with a tentative investigation into the genesis of granite andits relations with mineral resources.