Qaidam Basin was one of the continental petroliferous basins of Meso-Cenozoic in northwest Chi- na,and it had the same regional tectonic setting with Tibetan Plateau. Qaidam Basin,which was formed in specific structural boundary conditions,was located in the transitional zone of two huge convergence plates accompanying with peripheral orogenic zone,and developed in the passive plate boundary, which mean it was formed in the plate convergence enviffonment. Qaidam Basin respectively underwent two stages of com- pression from weak to strong in Meso-Cenozoic, which formed a series of structural patterns related to fold- thrust action. Therefore the formation of Qaidam Basin was the result of two actions,one was the subduc- tion-collision of Qaidam microplate to the north accompanying with south Qilian Mountains uplifting and the other was its thrusting-napping to the south accompanying with north Kunlun Mountains rising contin- uously. Through geological survey,seismic stratigraphy and analysis on oil-well drilling data,this paper il- lustrates a four-period evolution of Qaidam Basin since the Mesozoic Era. During the Early-Middle Jurassic epoch,the basin was under influence of block differences,the crust was stretched and a faulting-subsiding basin came into being. From the Late Jurassic Epoch to the Early Cretaceous Epoch,because of the closure of oceanic lithosphere and the collision of neighboring blocks, Qaidam Basin was under a compressive tec- tonic regime, which led to a turn-over of the early basin and the formation of a warping basin. At the age of Late Cretaceous Epoch Eocene Epoch,the new Tethys tectonic evolution led to the stretching of middle A- sia and the vast northwestern of China, and the whole Qaidam Basin settled down slowly. Since Oligocene Era, the powerful collision of Indian and Eurasian blocks compressed Qaidam Basin and made it as an extru- sion and uplift stage. Especially during the 4th stages of evolution,the Qaidam blocks at a distinct state ex- trusion and uplift, which ultimately formed the appearance as what it looks like today. Finally, analysis on the relationship between the tectonic evolution and oil and gas accumulation pointed out that the Qaidam Basin oil and gas exploration has good prospects.