New gravity model is urgently needed in place of the formerly-used two-layered model to achieve the purpose of interpreting correctly gravity data and obtaining results consistent with the real conditions. Based on the newest information and concept concerning crustal structure acquired through geologic and geophysical investigations, the authors suggest in the paper the application of crustal gravity model with variable density multi-layered structure. This model has the advantage of displaying different charateristics for diverse crustal layers in relatively simple forms. The latitudinal non-uniformity in a profile is determined by block. No apparent density interface exists betweent different layersj instead, there is gradient interface.From these data, the theoretical formula for a horizontal prism with cross section of non-isosceles trapezoid has been deduced with the corresponding pro gram compiled. The results of calculation made along Ganzhou-Yangshan of Jiangxi Province are quite in conformity with part of the data obtained form deep-seated seismic sounding. Practice shows that the choice of initial model is essential for acquiring satisfactory result.