Abstract: Based on an analysis of geochemical characteristics of Variscan weathered crust crude oil from Xiangtan 8 well, the authors hold that the crude oil bears the characteristics of high saturated hydrocarbon, low aromatic, no hydrocarbon and asphaltene, and light carbon isotope of the whole oil, and the hopanoid series of biomarkers bears the characteristics of high C30 hopanoid and relatively high gammacerane. All these features show that the kerogen type of hydrocarbon source rocks is good, the sedimentary environment is a reducing environment of high-salt, and the evolution degree of hydrocarbon source rocks is fairly high. The whole characteristics of biomarkers are consistent with the hydrocarbon source rocks of Xiangtan 9 well, suggesting a certain genetic relationship between the crude oil and the Carboniferous hydrocarbon source rocks.