In the past decades, significant advances have been made in the research on Re-Os isotopes. Re and Os can be concentrated from various organic-rich geologic samples, and hence the study of the Re-Os isotopic system in these samples has become a new hot spot in the field of isotope geochemistry. The organic matter, which is contained in organic-rich sedimentary rocks, is capable of absorbing and enriching Re and Os from the seawater. With the diagenesis of these organic-rich sedimentary rocks, the Re-Os isotopic system becomes closed, and the isotopic timing begins. If the hydrocarbon source rock becomes maturated, Re and Os would move with the organic hydrocarbon, and the Re-Os isotopic system could attain re-equilibrium. This paper deals with the principles of Re-Os isotopic system applied to various organic-rich geological samples such as black shale, oil shale, asphalt, schungite, oil and coal. Moreover, the potential disturbances of the weathering-leaching and the hydrocarbon maturation to the closure of Re-Os isotopic system are analyzed. In the aspect of practical application, several cases are cited to illustrate the significance of this isotopic system in the organic-rich system with the purpose of understanding such systems as environmental evolution, metallogenic process and hydrocarbon generation and accumulation. In order to help geologists and chemical analysts employ this isotopic system effectively, this paper has summed up the sampling and digesting methods for different samples. The Re-Os isotopic system in organic-rich geological samples should become a powerful tool in geological researches, but some problems remain to be solved in the near future.