The discovery of the Yan 9 oil bearing bed, Yan’an Formation， Middle Jurassic, has much enlarged the area of the exploration and exploitation region. The Yan 9 oil bearing bed is the main formation for more production in the Jingbian Oilfield. During exploration and exploitation, the Yan 9 oil bearing formation shows different responsible action with the same tech method (fracture and water injection and so on). The Yan 9 oil bearing bed is fluvial—lacustrine sediment, affected by source, transport and fluvial dynamic, showing different litho in north and south part of the studied area. In north part, the Yan 9 reservoir shows main sandstone as subarkose and feldspar sandstone, with high content fragment (82.0%~89.5%) of quartz and feldspar, with matrix composing of kaolinite, mica, siltstone, with cement of ankerite, siliceous and so on. In south part, the Yan 9 reservoir shows main sandstone as lithic feldspar sandstone and arkose, with high content fragment (83.0%~91.0%) of quartz, less feldspar, landwaste, mica and a bits of heavy mineral, with matrix composing of kaolinite and main cement of siliceous and carbonate. In general, the Yan 9 reservoir in in Western Jingbian Oilfield, Ordos Basin, shows well in porosity and permeability. As different type and content of fragment and cement, it is important to take different method respectively in exploitation way of water injection to protect reservoir from pollution and destroy.