Abstract: According to thin section identification,physical properties test,mercury injection experiment,X-ray diffraction and scanning electron microscopy(sem)analytical data,the research on tight sandstone reservoir characteristics of Sha-3 member of Shuangtaizi structure in Liaohe oilfield has been carried out.The results indicate the tight sandstone of Sha-3 member is characterized by low compositional maturity,low structural maturity,poor reservoir property and strong heterogeneity.The reservoirs are mainly of low-porosity low-permeability and low-porosity,ultra-low-permeability reservoir.The reservoir space types are mainly of intergranular pores,intergranular pore and intragranular pore,containing a small amount of micro pore,casting membrane pore,clastic particles within the intragranular dissolved pore and intergranular dissolved pore and less fractures.Pore throats are mainly with large,medium hole- micro and fine throat,the expulsion pressure is high,and pore structure is poor.Deposition and diagenesis are two main controlling factors of reservoir physical properties,among which the reservoir with comparatively coarse granularity,better separation,sublacustrine fan,braided channel microfacies is better.Cementation and compaction are the main reasons for poor reservoir physical properties.The dissolution plays a constructive role in the increase of reservoir porosity on one hand and on the other hand,the corrosion product of in-situ precipitation greatly reduces the reservoir permeability.