Abstract: At present the lower Yanchang formation of Ordos basin has become the key area for petroleum exploration and development.In Fuxian area,the oil reservoir types are mainly of structure-lithology type.Based on the outcrop,core observation,casting thin sections,mercury injection,etc,of Chang-8 reservoir in the research area,and in combination with logging data,the research on reservoir petrology features,physical properties and pore structure characteristics have been analyzed.The study results show Chang-8reservoir types are mainly of feldspar sandstone,the reservoir pore structure types are mainly intergranular pores,feldspar dissolved pore comes the second.The pore throat structure characteristics is given priority to micro pore throat types,the reservoir physical property is poor.Therefore,it belongs to low porosity,low permeability reservoir.Reservoir physical properties are characterized by the dual factors of diagenesis and sedimentation.