It is one of the challenges to investigate the relationship between Tibetan uplift process and hydrocarbon preservation mechanism in the current petroleum exploration theory and practice. For this study, systematically technique and method of fluid inclusion have been employed to analyze the 51 reservoir rock samples which are taken from the outcrops of Changdu basin in the northeastern Tibet. Eventually, the paleo-oil reservoirs charged with four events during foreland basin stage from the early Jurassic to the early Cretaceous in the Triassic and Jurassic grey fine sandstones have been firstly unraveled, which had been destroyed or cracked into bituminous sandstones during the strike-slip and pull-apart basin stage of the Cenozoic. Meanwhile, abundant pure vapor fluid inclusions with weak white-blue fluorescence and being coeval with aqueous inclusions of high homogenization temperature in trails of sandstones, calcite and quartz veins both in the Paleozoic and the Mesozoic reservoirs, which is surely implying for natural gases migration and accumulation happened widely in basin during the Cenozoic. It is, therefore, suggested that natural gas is the object for seeking and the southern Mangkang depression in the basin with relative good preserving condition would be the favorable site for gas exploration.