The sandstone reservoirs of N₂² and N₂¹ in Yingdong Oilfield are characterized by much and thin layers and fine-grained,which play an important part on hydrocarbon distribution. Based on core, thin section, scanning electron microscope, mercury penetration and X-ray diffraction, reservoir characteristics and main controlling factors of N₂² and N₂¹ sandstones in Yingdong Oilfield were systematically studied. The result shows that: ①N₂² and N₂¹ sandstones are lithic arkose, mainly of fine-grained sandstone and siltstone, with medium compositional maturity and high textural maturity. Matrix content is low, and as the main type of cement, calcite content is moderate. Diagenesis of the sandstone reservoir is weak. ②the main reservoir space is primary intergranular pore, followed by dissolved pores and intragranular crack. Pore structure of reservoir includes three major types: medium pore and throat, large pore and medium throat, large pore and coarse throat. ③High quality reservoir in the study area is attributed to shallow burial condition. Microfacies, sandstone texture and cement content are key factors to distinguish good porosity and permeability sandstone. Compaction is the main factor for porosity-losing processes, and calcite cementation comes next. ④the reservoir in Yingdong Oilfield can be subdivided into four classes,and class Ⅰ, Ⅱ and Ⅲ are commercial, while Class Ⅳ is noncommercial and requiring improvements. It is suggested that while there is sandstone there is reservoir, and the key of exploration is searching sedimentary facies of high quality.