Dongzhi-Zhengning area is a new Mesozoic petroleum exploration target in the Ordos Basin. In this paper, biomarker compounds in oils from the region and Mesozoic source rock from Ordos Basin were systematically analyzed. The genesis of the oil was discussed by studying the geochemical characteristics of these biomarker compounds. Similar geochemical features of oils from Dongzhi-Zhengning area suggest generation from a source with mixed terrigenous and algal-bacterial organic matter. The biomarker distributions of the oils show that they were formed under a weak reducing and freshwater environment. Molecular maturity parameters indicate that the crude oils are mature. The results of oil-source rock correlation showed that the oil was mainly derived from Chang-7 source rock.