With the methods of rock section, cast section, scanning electron microscope, pressured mercury testing data we made a deep research of the Zhiluo oilfield Chang 8 reservoir's lithology, physical properties, pore throat structure and pore throat types in the paper. This study trying to make a clear inquiry of this area's reserve property and which lay a significant foundation for the further work. The result defines the Chang 8 reservoir, deposited in subaquatic distributary channels, are mainly made up of feldspathic sandstone, debris- feldspathic sandstone. With interparticle pore, intragranular dissolved pore and intercrystal pore, the reservoir is characterized by low compositional maturity and middle texture maturity, which had a poor physical property and it is typical low porosity and low permeability reservoir. In the plane, the reservoirs' physical property is controlled by provenance and sedi- mentary face zones, in vertical direction, the compaction and cementation lead poor reservoir's physical property and dissolution is favorable to reservoir property.