Abstract: The lithologic characteristics, physical properties, pore structure and their controlling factors of the XW6 reservoir in the Weizhou Formation in the eastern Maichen Sag were studied based on thin section observations, scanning electron microscopy and X-ray diffraction analysis. The physical propertiesof the Weizhou Formation aregenerally poor with the second member featuring fine grain size, medium-poor sorting, medium porosity, medium-low permeability and medium-narrow throat diameters. The third member has coarse grain size, poor sorting, ultra-low porosity, super-low permeability and microthroat diameters, indicating less favorable physical properties.The controlling factors for physical propertieswere summarized as follows. Compaction made the physical propertiesof the reservoir become worse. Hydrocarbon filling was beneficial for the generation of dissolved pores and the preservation of porosity and permeability. Sedimentary micro-facies and rock type played a very important role in reservoir physical properties.