Abstract: Geologic conditions and characteristics of marine facies petroleum in South China have put forward new contents and requirements for petroleum source condition analysis.For late accumulations,prescription of source rocks is more important than their original characters.Spurning the former rules which adhere to parameters,source condition analysis and source rock evaluation should be based on source rock evolution history research and focus on stage and prescription studies.When effective source rocks and generation regions are confirmed,exploration targets can be chosen.In marine facies strata in the Jianghan plain region,sealing system rebuilt from late Yanshanian to early Himalayan period is the main exploration target.Superimposition of rift-subsidence basins makes Permian source rocks become mature and Lower Paleozoic source rocks again produce petroleum.Permian carbonate source rocks are the main effective source rocks.From Wufeng Formation of Upper Ordovician to Longmaxi Formation of Lower Silurian is the second effective.Main source regions locate in the Jiangling and Qianjiang sags.