Abstract: Based on field geological properties and chemical analysis results,the metallogenetic factors and genesis of high-As coal in southwestern Guizhou Province are disscused in this paper.According to the analysis of ore-forming geological factors,the formation of the high As coal was restricted by various orecontrolling factors,such as the magmatic rock factors,the sedimentary facies and paleogeographic factors,the lithological factors,the structure factors,and so on.It can be considered that the enrichment of arsenic may be divided into four stages:stage of the ore source bed formation,stage of the Longtan coal-bearing rock series formation,stage of the ore-bearing hydrothermal formation,stage of the high arsenic coal deposit formation.