Abstract: Northwest China is one of the most abundant areas in oil shale in the nation,where oil shale is widely distributed in a number of large sedimentary basins such as the Ordos,Zhungerer,Tarim,Qaidam and Ejina-Yingen,and also some medium-small size basins such as the continental facies intermontane basins in the Daqingshan and Yinshan areas as well as in the Qilian-Hexi Corridor (west to the Dunhuang basin,east to the Liupanshan basin-Bayanhot basin,south to the Qaidam basin,including many Meso-Cenozoic sedimentary basins with Paleozoic basement).By analysis of formation conditions and genetic type of different sedimentary basins in northwest China,The author proposed three genetic types of oil shale:deep lacustrine-moderate lacustrine facies,marine-continetal interactive facies and swamp facies. It is suggested that the deep lacustrine-moderate lacustrine facies of large inland basin is the most favorable exploration targetbecause of its steady sedimentary environment,abundant organic matterand other characteristics such as wide distribution,great thickness and steady oil content which made oil shale deposit much easier.