Re-Os isotope geochronometer has achieved a lot in getting absolutely precise ages of petroleum generation and Organic-Rich Sedimentary (ORS) rocks. And what’s more, the initial 187Os/188Os ratios can be utilized as an oil to source fingerprinting tool in the oil-source correlation. This paper analyzed the principles of Re-Os isotope dating methods applied in Organic-Rich Sedimentary systems, and discussed the various factors of influences on the Re-Os isotope system. Those geological processes such as the maturation of hydrocarbon, biodegradation and water washing and the progressive precipitation of petroleum asphaltenes had very little effect on Re-Os isotope system. However, Re-Os isotope system could be disturbed by Thermochemical Sulfate Reduction (TSR), hydrothermal fluid and the contamination of mantle-fluid. The main problems of the research on Re-Os isotope in petroleum system at present can be attributed to two aspects: ①the understanding of geochemical behavior of Re and Os in organic maters; ②how to get precise Re-Os isotope ages and the interpretation for the ages. In terms of these two aspects, carrying out the research of the relationship between Re-Os data and organic faces and modern algae may help the better understanding of Re-Os geochemical behavior and their enrichment mechanism. The research about the factors (e.g. depositional environment and organic type) that control Re-Os fractionation may provide a method to know which stratigraphic sections and which samples to utilize for Re-Os geochronology.