The sand ofChang 8 reservoir ofUpper Jurassic Yanchang Formation in Zhenjing area belongs to tight and low permeability reservoir. Based on the analysis of cast thin section, cathodeluminescence and scanning electronic microscope, this paper studied the characteristics and types of diagenesis ofChang 8 reservoir. The results showthat the sandstone reservoir in this area mainly experienced compaction, cementation and dissolution, the diagenetic evolution reached the middle diagenetic stage A, and reservoir physical properties were controlled by digenesis. Mechanical compaction and carbonate cementation are the major destructive diagenesis, the chlorite rimon the grain surface plays a constructive role in protecting primary intergranular pores, and the secondary pores created by dissolution of feldspar
improve the reservoir properties.