Subei Basin is an only basin in the eastern region of China in which hydrocarbon of the Upper Cretaceous is discovered up to new. The aromatic compounds are determined by Gas Chromatograph-Mass Spectrometer (GC-MS) in 20 oil sands and one oil sample from the Upper Cretaceous Taizhou formation. The series of triaromatic steroid are main aromatic fractions, and indicate the salt water deposition environment of parent materials and low-mature crude oils. The low abundance of biomarkers from higher plant reflects that the crude oils are mainly from the sapropel parent materials. The relative content of aromatic fraction, the relative content and ratios of three fluorene series, and the ratio to dibenzothiophene/phenanthrene suggest that the parent materials of crude oil are formed in the strong reduction environment of salt water. The geochemical characteristics above mentioned are common; however the differences of parameters show that crude oils were from the different source formations. The crude oils of the Taizhou formation could be divided into two groups by the components of aromatic hydrocarbon and the relation of fluorene, dibenzofuran, and dibenzothiophene. The crude of the Taizhou formation at Hai'an Sag and those at the north slope of Gaoyou Sag belong to the one group and come from the Cretaceous Taizhou source formation; however crude oils at Wubao Uplift belonging to another group are from the Paleogene Funing source formation. By using the ratio of vitrinite reflectance (R_o) calculated by methyl dibenzothiophene, it is estimated that the crude oils at Hai'an Sag source come from low-mature hydrocarbon kitchen of the Taizhou formation, and the crude oils at the north slope of Gaoyou Sag source come from the nearest low-mature hydrocarbon kitchen of the Taizhou formation, but the crude oils at the Wubao Uplift source come from the mature hydrocarbon kitchen of the Funing formation at the adjacent deep depressed zone of Gaoyou Sag. The results are of significance for the petroleum exploration at Subei Basin.