Abstract: Researches on the analytical data more than seven thousands of Mesozoic samples from the Qiangtang Basin in Qinghai-Tibet Plateau show that the Jurassic source rock is still mature and generating oil in the center of Qiangtang Basin.The Jurassic source rock is more and more mature from the center to the margin of the basin.Almost all the T₃x source rocks are high-mature to over-mature and the range of oil generation has already very small.The maturity of the organic matters in this basin is mainlly controlled by the palaeo-geotemperature,the degree of tectonic deformation and pyrogenetic rock and plutonic hot fluid.In the center and the east of the basin,the main influential factor of organic matter's maturation is the maximum palaeo-geotemperture or palaeoburial depth.Near the fault or folded zone in the basin and the margin of the basin,organic matter's maturation is mainlly affected by the strongly unbalanced pressure.And in the west of the basin,the plutonic hot fluid in the basement fracture zone may be the main influence factor of organic matter's maturation.There are two (or three) hydrocarbon-generating processes occurring in the Late Jurassic-Early Cretaceous and the time of Tertiary sedimenting.In particular,the hydrocarbon-generating process caused by the Jurassic source rock in the Early Miocene to the Late Miocene is more favorable to the petroleum exploration in this basin.