The Xu-6 reservoir of Xujiahe formation in Guang’an area are fluvial sendiments,and the reservoir with best physical property are developed on the main branch river channel of the deltaplain.The reservoir rocks are mainly arcose and lithic sandstone,which are of low porosity and low permeability characteristics.The reservoir spaces are mainly original residual intergranular pores,and the secondary intergranular or intragranular pores.The study shows that the affection on reservoir of sedimentation are mainly by the controlling of sand distribution,rock fabric and physical property and so on.The physical property obviously decreased by the reconstruction of intensely compaction,pressolution and cementation,but the dissolution of feldspar in buried period improved the spaces.