Abstract:The Mengyejing potash deposit in Yunnan Province is till now the only solid potash deposit discovered in China. Inspired by the theory of "deep penetration" and biogeochemistry, a biogeochemical method is preliminarily studied for potassium prospecting in the Mengyejing deposit area and its surrounding areas. A total of 71 plant samples (leaves of tall trees) were collected from the research areas. Over complicated sample preparation (including washing, air-drying, grinding, screening, chemical digesting), determining, data processing and analyzing, the background values of major and trace components for plant samples were obtained, and meanwhile the anomaly areas were preliminarily delineated, which are in good agreement with the prospect areas delineated in former studies. Further sampling and more research work need to be carried on in order to offer more useful data and techniques for potassium prospecting, as well as other ore deposit prospecting.