Permian deposits are main hydrocarbon source rocks in current petroleum exploration in the Junggar and Turpan-Hami (Tuha) basins, and their understanding is directly concerned with petroleum potential evaluation in the region. Analysis of the total amount of global organic carbon, size of the lake basins and organic geochemistry of crude oil and source rocks shows that there exists no megalake basin in this region but only a large inland lake composed of a number of sub-basins.