Based on the fully recognition about stratigraphical and sedimentary characteristics of the lower sandstone member Kepingtage Formation of Silurian in Tazhong Area, Tarim Basin and by using large number of thin-sections and cores, the lithology and reservoir characteristics have been studied and the reservoir developing characteristics with main control factors have been illustrated. The characteristics of the reservoir are as follows: Sand body of lower sandstone member of Kepingtage Formation primarily consists of both fine-grained lithic sandstone and lithic quartz sandstone, with low composition maturity, rich pore-filling contents, high-rounded, and well-sorted. The main pore types are original intergranular pore, intergranular emposieu, and micro-pore. The porosity ranges from 0.5% to 14.7% and the permeability ranges from 0.1×10^-3μm² to 100×10^-3μm², therefore the reservoir is characterized by over-low porosity and permeability. Sedimentary environment, deep-bury, and lithgenesis function (compression, carbonate, cementation) are main factors that control the reservoir characters.