Abstract: Changjiang Sag has huge sedimentary deposit, the maximal thickness is 8800m, dark mudstone of lacustrine deposit predominate Tertiary, having good generating conditions.The abundance of organic matter is mid-high and the types is Ⅲ.Most source rock belong to innacle phase.The main generating hydrocarbon center of Changjing Sag is Daguanyuan deep sag, the area is 6758.75km², available source rock is big, covering vast area, the maximal sedimentary thickness of Cenozoic is over 5000m, the amount of generating hydrocarbon is 7.219×10 8 t, the amount of oil-gas resource is 1.674×10⁸t, many tectonic in there, and it is good prospective area in Changjiang Sag.