Abstract: Mengyejing salt mine in Jiangcheng of Yunnan Province is the only solid potash deposit founded in China. The geological structure is relatively complex in this area. Through geological,geophysical and drilling exploration, the authors thought potash beds were squeezed up to the surface layer, along with the faults from the deep Jurassic potassic rocks, and there may be salt sources or more large ores under the deposit. In order to realize the ore exploration breakthrough, the deep structure and characteristics and 3D structure model of salt rocks need studying. The basement changes and fault distribution of the Jiangcheng basin were obtained using potential field separation, multi-scale edge detection and 3D physical inversion to process and interpret the high precision gravity data. And other information such as the structural framework, 3D distribution of density of underground body and the relationship with salt mine distribution was also obtained. The authors deduce that there may be salt mine and potassic salt ores below the deep northwestern Mengyejing ore field, so this area should be the key area for the following exploration of potassic salt. These results will provide clues and direction for Jiangcheng potassic prospecting in future.