Objectives: Based on analysis of the existing oil and gas exploration results, fault characteristics and structure setting, we studied the Ordovician oil/gas distribution and key factor controlling accumulation of the Tazhong II area in the Tarim Basin.Methods: This study used various data such as routine logging, seismic data and geochemical data.Results: Oil and gas properties have saddlelike distribution in plane: compared with the area between the two fault belts, there are significant parameter abnormities in the Tazhong No.1 fault belt and Tazhong No.10 fault belt, as shown by relatively low density, high wax content, high GOR, high dry coefficient and high H2S content. Hydrocarbon generally distributed in the Ordovician weathering crust karst reservoirs with limit thickness (300 m).Conclusions: The unconformity of Yingshan Formation’s top controlled the reservoir depth vertically, and the reservoir inhomogeneity is the important reason for the differential oil/gas distribution in plane. The faults improved the physical properties of reservoirs and transport the hydrocarbon, which control the hydrocarbon charge intensity and hydrocarbon phase behavior distribution. The microstructure in the slope determined the differential oil/gas distribution, which show that hydrocarbon first enrich in the high part.