According to the thin section authentication, X-ray diffraction, mercury injection, two phase relative permeability and nuclear magnetic resonance (NMR). it is concluded that: He 8 reservoir was a typical tight sandstone gas-formation, with average porosity 8.4%,permeability 0.81 mD. Dissolution pores with surface porosity 3.5% developed most. The intragranular dissolved -intracrystalline pore was the main combination type. In terms of Mercury Injection Parameters Curve characteristics, the favorable reservoir is mainly the type II. Sometimes, because of crack, reservoir with high permeability, low saturation characteristic in the study area. There are serious fine throats in type II reservoir, with no contribution most. Although the throat than 0.86μm account for only 21%, but contribution to permeability of 78%; the structure of pore-throat is bad with pore throat radius ratio 484. In additionally, He 8 reservoir, with strongly water wetting. As long as the gas saturation of reservoir is higher than 15%, the natural gas can flow under the appropriate pressure drop, the movable fluid saturation of the reservoir are generally less than 35%. Hence,improvement measures are essential to improve the yield of gas.