Abstract: The sandstone framework detrital composition characteristic,the ratio map of sandstone,directions of palaeo-flow,sandstone petrography,constant elements,trace elements and sedimentary structure feature were used to analyze source rock,source direction and tectonic discriminent of Shanxi Formation in the west edge area of Ordos Basin.The petrographic characteristics of sandstone show that the sediments are mainly carried from the North of the basin,where occurred granite,metamorphic rocks,gneiss and other rocks.According to the data of constant elements and trace elements,the tectonic environment is the passive continental margin.It is indicated that as Permian Shanxi Formation deposited,the sediments were carried from northern Yinshan area and northwestern Alashan mass.