Samples are two oil-bearing extracts from Jurassic oil sandstone reservoirs in Well LV in North Yellow Sea basin. By analysis results of conventional organic geochemical methods and stable carbon isotopic detection, it is shown that their geochemical characters are different. The deeper oil extract belongs to common oil, in which the n-alkane is predominant fractional composition of saturate hydrocarbon, and the n-alkane curve shows normality distribution with low carbon number predominance. While the shallower oil extract indicates strong biodegrade. The gas chromatograms (GC) of the saturate hydrocarbon raises baseline from UCM, and also contains the complete low carbon number n-alkane, Pr and Ph. The carbon isotope(δ13C) values of whole oil (oil sandstone extract) and group composition ranges from-24.7‰ to-32.3‰. The δ13C values of whole oil and asphaltene have heavy carbon isotopic ratio, while saturate hydrocarbon and aromatic hydrocarbon have light carbon isotopic ratios. The biomarkers relating with maturity parameter show that the two oil sandstone extracts have arrived to mature or highly mature stages. Deduced from biomarkers and carbon isotopes, the matrix of the oil sandstone extracts were deposited in a shallow lacustrine environment so that it was controlled by terrestrial higher-plant debris and the lower aquatic organisms. Comprehensive analysis indicates that hydrocarbon was charged twice in these areas.