In order to study the reservoir characteristics ofChang 7-Chang 9 reservoir group in Wuqi and Dingbian area of Ordos Basin, the data of thin section, grain size, mercury penetration and physical properties are used to analyze the petrology, pore configuration, physical properties of the reservoir. The effects of sedimentation and diagenesis on reservoir properties are also studied. The result shows that the reservoirs of Chang 7-Chang 9 reservoir group are mainly of lithic arkose, the pores are mainly corroded intergranular pores, the porosity ranges from8% to 12%, and the permeability ranges from 0.1mD to 1mD. Compaction makes the primary pores decrease, cementation not only damages the primary pores, but alsomakes the secondary dissolved pores suffer damage, and dissolution improves the reservoir properties.