Jurassic Sangonghe sandstones (J₁s) are prolific oil reservoirs in the Mosuowan area of the Junggar Basin. However, hydrocarbon exploration in deep-buried sandstones with depths > 4km would be highly risky due to the reservoir quality. Analysis of diagenesis can provide insight into controls on reservoir quality, which helps to reduce exploration risks and predict reservoir quality in perspective area. Routine core analyses and petrographic data were used to investigate diagenesis and their impact on reservoir quality of the J₁s sandstones. J₁s sandstones are mostly feldspathic litharenite and litharenite with an average composition of Q₃₆F₂₀R₄₄. A wide range of porosity from 5.3 to 16% (average 11.6%) and permeability from 0.14 to 566mD (average 6.27mD) indicate that the reservoir has strong heterogeneity. Eodiagenetic events are characterized by mechanical compaction, chlorite grain coating, and calcite cementation. Mesodiagenetic events include feldspar dissolution, quartz overgrowth, kaolinite and illite precipitation, and ferrocalcite cementation. Mechanical compaction played a more prominent role in the reduction of porosity than cementation. Grain size and detrital component influence diagenetic compaction process which resulted in the difference in sandstone porosity reduction and variance in porosity-permeability correlation. Secondary porosity was generated mainly by feldspar dissolution. However, mass-balance calculations suggest almost equilibrium in aluminum of the system, indicating that burial dissolution contributes few to net porosity increase. Coarser-grained sandstones with more rigid grains and fewer ductile rock fragments are subject to less mechanical compaction which can preserve more intergranular pores. The coarser-grained sandstones have better reservoir quality than finer sandstones, which can be reflected by the higher slope in the porosity-permeability correlation.