Geospatial knowledge discovery is a branch of knowledge discovery, at the same time, knowledge management(KM) is an important concept in management field, so after discussing the basic theory on KM, knowledge management systems(KMS), and geospatial knowledge discovery, this paper introduces them to the geospatial information field, brings forward the theoretical framework of spatial knowledge management(SKM) and spatial knowledge management system(SKMS), and explores the method of geospatial knowledge discovery method based on SKM, mainly elaborating the definition and normal process of SKM, giving the concept, overall structure and main function modules. Finally, it brings a case study on precision agriculture, designing precision agriculture KM and knowledge discovery system based on “3S”, including the functions, knowledge base of agricultural, architecture of its SKMS, and operation principles of precision agriculture, as well as giving two specific operation instances, which provides a new approach for geospatial knowledge discovery.