On the basis of the previous studies and data from over 20 outcrops,over 150 wells and 12 000 km seismic profiles,especially new drilling data,the lithofacies palaeogeography of the Jurassic in the Qaidam Basin was restudied. Based on the lithofacies palaeogeography maps compiled,the distribution characteristics of Jurassic strata and sedimentary facies was pointed out,the position of hydrocarbongenerating sags and sandstone reservoirs was determined,and the  hydrocarbon potential of the Jurassic was predicted. It was concluded that early and middle Jurassic humid and warm climate was favourable to the deposition of source rocks,and that supply of clastic material from several uplifts was advantageous to forming the sandstone reservoirs. Six types of the sandbodies,i.e. braided stream delta sandbody,shore lake sheet sandbody,shore and shallow lake beach and bar sandbody,fluvial channel sandbody,turbidity fan sandbody and nearshore submerged fan sandbody,and 30 advantageous sandbodies were determined. The source rocks deposited in a lot of semideep and deep lakes supplied abundant hydrocarbons,and the 8 source sags of different sizes totally over 4 000 km2 in area were located. The evolution of the palaeogeography shows that many types of sourcereservoircap rock assemblages were developed in this area. It was pointed out that the Lenghu,Kunteyiand MahaigaxiuYuka areas are favorable for hydrocarbon exploration in the future.