Abstract: The Poshan silver deposit is a typical extra-large stratabound deposit of metamorphosed elastic rock type. Located between the Nanyang and Wucheng basins,it experienced a long and complex geological history and multi-phased formation and evolution. On the basis of sedimentation,diagenesis and metamorphism,its ore-forming processes were suffered superposition of succeeding hydrothermal process and the main mineralization was Caledonian geothermal water leaching and enrichment. The ore-forming material came from the upper and middle Waitoushan formation of the Neoproterozoic. The distribution of the major ore-forming elements display obvious zoning phenomenon-silver enrichment in the upper portion,while zinc in the lower. The element assemblage anomalies of Ag,Pb,Zn,Cd,As,Cu,Mn, and (Sb)are associated with the deposit in the surrounding areas. Based on the summarization of the primary geochemical anomal characteristics of the deposit,the authors have established a model for the primary geochemical anomalies and geochemical criteria for ore prospecting.