Abstract: Abstract：Through the analysis of casting thin sections and pore microscopic images, combined with scanning electron microscopy and cathodoluminescence images, the reservoir microscopic characteristics of J1s2 in Moxizhuang area were studied, which included reservoir petrology, pore types, diagenesis etc. In addition, the factors responsible for the formation of low permeability reservoirs and the main controlling factors of relatively high quality reservoirs were analyzed. The results show that the sandstones are mainly feldspathic-lithic sandstones with low ingredients maturity, with a small amount of lithic sandstone. The soft debris has experienced strong plastic deformation, thus looking like matrix, which remarkably affects physical property and oil-bearing property of the reservoir. The pore type is mainly secondary pore and subordinately primary pore. Strong compaction, weak calcite and kaolinite cementation are the main factors responsible for the low permeability reservoirs. The high quality reservoirs have such microscopic characteristics as coarse grain size, low content of soft debris, weak calcite and kaolinite cementation and strong dissolution. So the main factors controlling high quality reservoirs should include the content of soft debris, late dissolution, and favorable sedimentary facies. In addition, the channel sand body cycles in the middle and lower reservoir are the favorable parts of the effective reservoir.