The Sulige Gas Field in Ordos Basin has the characteristics of low permeability and low porosity，which is the most typical tight sandstone reservoir in China. According to core data from the Lower Shihezi Formation，Shanxi Formation and Taiyuan Formation of Permian system in the eastern Sulige Gas Field of Ordos Basin，experimental observations and statistical analysis were carried out on tight sandstone reservoir from the respects of geological genesis，petrological characteristics，reservoir space types and reservoir physical properties by using scanning electron microscopy，casting thin section analysis and so on. This research shows that the main reason for the formation of tight sandstone reservoir in the eastern Sulige Gas Field is strong compaction caused by deep burial depth. The reservoir pore evolution process is mainly influenced by compaction and authigenic cementation. The kaolinite has the highest content among all the clay minerals，which is easier to fall off and fill the intergranular pore and thus plugs the pore throat. The flaky illite and chlorite can fill pores，which leads to the formation of tubular throat or the segmentation of the throat. The cementation of other minerals and the strong water sensitivity of montmorillonite reduce the gas permeability. In addition，the proportion of primary pore is very low. The rock particle sorting is poor and the clay minerals fill the intergranular pores，which leads to complex relationship between pore and permeability and the reduction of the formation permeability in tight sandstone gas reservoir. The tight reservoir space are mainly lithic dissolved pore，the intercrystal pore and feldspar dissolved pore in the eastern Sulige Gas Field.