Abstract: Qiangtang basin lies in the north and mid of Qinghai-Tibet plateau,which locates in the mid-segment in the global Tethys domain with the abundant reservoirs of oil/gas.It is a compound and symmetry foreland basin.It has widespread Mesozoic marine deposition and the latest marine strata were developed in China.The thickness of marine strata is ten thousands kilometers,half of it is Jurassic strata.The basin underwent 4 major sedimentary stage:the late Paleozoic continental margin stage,the Triassic inter-continental rift valley stage,the Jurassic continental margin sedimentary stage finally,tectonic squeeze-erosion stage since Bangong-Nujiang suture closed at the end of Jurassic.Mesozoic Qiangtang basin has widespread and high quality source rocks.The thickness of source rocks is huge;the most thick can be up to 3 kilometers.The organic matter type of source rocks is perfect and its abundance is large.The organic matter maturity varieties from mature to overmature in Xiaochaka formation of upper Triassic and Buqu formation and Xiali formation of mid-Jurassic.The burial conditions of source rocks is a relative good,and oil production is extremely large.The Mesozoic source rocks are one origin of oil and gas in Qiangtang basin.