Abstract: Based on the thin section identification，scanning electron microscope，physical property and pore structures，this paper discusses the reservoirscharacteristicsand controlling factorsof Member 3 of the Liushagang formation in WZ10-A oilfield and surrounding areas，Weixinan sag in detail.Our result shows that the sandstones types of member 3 of Liushagang formation is feldspar quartz sandstone，the rock types intervals are gravel-bearing sandstone and fine sandstone.The dominant reservoir space was intergranular pores and intergranular dissolved pores，followed byintergranular dissolve pores，and rare fractures.The sandy conglomerate has ultra-low porosity and ultra-low permeability reservoir，and middle porosity and ultra-low permeability reservoir.Lithology，sedimentary facies and diagenesis are the factors affecting reservoir property.Comprehensive analysis shows thatthe medium-coarse sandstonesare highquality reservoirs，the beach bar，distributary channels，distributary channel of fan delta front and riverway are fine reservoirs.It is the target of exploration and exploitation.