Abstract: The microscopic pore structure of tight sandstone reservoir is complex, the parameters of microscopic structure characteristics obtained by the conventional method are difficult to characterize the reservoir properties and the movable fluids. Based on the conventional methods of the cast thin section, the scanning electron micro-scope, and the physical properties analysis, the unconventional methods such as constant velocity mercury injection and nuclear magnetic resonance(NMR) were adopted to determine the parameters characteristics of reservoir microstructure pore structure and the relationship between the physical properties and movable fluid saturation. The results show that the throat radius is not related to the reservoir physical property, the throat radius and pore-throat ratio are the main factors affecting the reservoir permeability and seepage ability, among which the lower the permeability, the higher the extent of the throat radius, when the permeability is higher, the pore-throat ratio influence degree is higher.