Northwest China had experienced three major development stages

i.e.plate diver-gence from Middle Proterozoic to Early Paleozoic;plate convergence from Late Paleozoic to the end of Triassic;basin-mountain mechanism from Jurassic to Quaternary.The transformation between the tectonic mechanisms of oceanic and continental lithospheres

together with the influence exerted by the Tethys Plate since Meso-Cenozoicresu lted in three type basins(tensional

compresional and strike-slip.basins)and eleven subtype basins.Multicycle is the basic characteristic of the superimposed basins in this area.The basins extended first and then compressed

thus forming double-layer structure in verti-cle.The extention provided ideal place for the deposition of source rocks and the compres-sion prepared necessary condition for hydrocarbon migration ahd accumulation.