On the basis of sedimentary organic facies study and source rocks fine classification, we select the excellent source rocks of different maturity from the 4th Member, Shahejie Formation, Palaeocene (E2-3s4) and set up a natural evolutionary geochemistry section. Using material balance method, the original organic matter contents are recovered and the petroleum expulsion efficiency is quantitatively studied. According to the quantitatively calculation, the expulsion efficiency of the excellent source rocks in principal hydrocarbon supplying stage are high and can reach 70%~80%, and the original organic matter content recovery factor of the deep zone can reach 1.5~2.0. These results will bring important influence to the total resource and resource distribution evaluation. The total hydrocarbon content generated and expelled will be higher than previous study, with the source rocks in the deep zone will be significantly higher than before. These result imply that the principal effective hydrocarbon source rocks will be more deep than previously believed. So the study has great significance to the resource reevaluation and deep zone oil and gas reservoir exploitations.