Ordos basin Jiyuan area Chang 82 reservoirs with low porosity, low permeability reservoir. using the data of core, logging and sandstone thin slice，type reservoir petrology, pore types and physical property characteristics analysised shows that the Chang 82 reservoir types for feldspar lithic sandstone and lithic feldspar sandstone; Grained sandstone mainly in fine sandstone and fine sandstone; Pore types mainly intergranular pore, followed by solution pores, reservoir belongs to the micro pore throat type. Further research shows that reservoir characteristics and the development of high quality reservoirs are controlled by sedimentary and diagenetic dual role: sedimentation in the form of fine sandstone and sandstone porosity were similar, while the permeability difference, the thick sandstone physical property is better than that of thin layer sandstone physical property; Diagenesis causes river in central microfacies development chlorite membrane, save a lot of intergranular pore property is good, a thin layer of channel main body strong compaction and cementation microfacies, reservoir physical property is poor.