Mesozoic marine Qiangtang Basin, lying on the Qiangtang Terrane, generally has the features of median mass basin. It can be divided into five first-order tectonic units: northern Qingtang depression, western uplift, middle lower uplift, southern Qingtang depression and northeastern slope zone. Qiangtang Basin has experienced three evolution stages which are Triassic marine basin, Jurassic—early Early Cretaceous marine basin and late Late Triassic tectonic transition during the above two stages. The Triassic basin with its basement higher in south and east, controlled by the opening and closing of Lazhulong-Xijinwulan tectonic belt on its north side, is characterized by volcanic, clastic, carbonate, gypsum-salt rocks and coal-bearing clastic rocks. At the end of Late Triassic, responding to the closing of Lazhulong-Xijinwulan ocean and collaging of Qiangtang Terrane and Kekexili Terrane, this marine basin uplifted as a whole and there followed a sedimentary hiatus with the formation of karst weathering crust, after which this region underwent regional rifting and volcanic activity, indicating the formation of Bangonghu-Dingqing intercontinental rift. During Jurassic, Qiangtang Basin once again subsided and received marine sediments, approximately synchronous with the development of Bangonghu-Dingqing intercontinental rift on its south side, indicative of the marine transgression from south to north. The Jurassic marine basin developed multiple NWW-trending depo-subsidence centers, with higher relief in southwest and northeast and relative subsidence centers in east part of southern Qiangtang depression and central-west part of northern Qiangtang depression. Jurassic basin was characterized by clastic, carbonate and gypsum-salt rocks. In early Cretaceous, the convergence between Gangdise (Lhasa) Terrane and Qiangtang Terrane and the closure of Bangonghu-Dingqing intercontinental ocean put an end to the marine sedimentary history of Qiangtang Terrane and since then Qiangtang Terrane stepped into continental sedimentation of several small basins. Late Early Cretaceous—Late Cretaceous basin inversion and Cenozoic modification largely reformed the original appearances of the Mesozoic Qiangtang Basin and its north and south suture zones, and disappearance of the northwestern part of the basin. The superposed evolution and modification of Qiangtang Basin creates favorable conditions for Mesozoic marine successions to contain multi-set source rocks, have high oil-gas exploration prospect and form multi-layer and multi-type petroleum accumulation. The discoveries of several different kinds of oil-gas shows and large paleoreservoirs indicate and prove the ever-existing processes of hydrocarbon formation and accumulation in Qiangtang Basin. In conclusion, late modification is the main factor influencing the hydrocarbon accumulation and distribution, resource quantities and prospect, and exploration effectiveness of Qiangtang Basin.