Abstract: Yingen-Ejina Basins in the west of Nei Mongol is shown by superposition of Mesozoic and Cainozoic on basement of pre-Palaeozoic constitutes.Its evolution of the tectonism include hump and fission in high temperature stage in Triassic,initial rift valley devopment stage in the Early and Middle Jurassic,rift basin devopment stage in the Early Cretaceous,open and sag stage in the Later Cretaceous and convergent and extruding stage in continent from Tertiary to Quaternary.In these process of evolution,it deposited mainly hydrocarbon source rocks of lacustrine facies in the Early Cretaceous and secondary coal measures source rocks in Early-Middle Jurassic.The basin can be divided in to three types such a sentire superpo sition,basic superposition and displaced superpo sition according to the superposition correlation among of the tectonic layers.