At present, the experiment methods of low temperature nitrogen adsorption in shale reservoir pore structure have been widely used. But the interpretation of the adsorption stripping curve about the type of shale reservoir microscopic pore structure is chaos. Based on this, the mechanism and characterization of low-temperature nitrogen adsorption experiments in shale microscopic pore reservoir was emphatically discussed, and the typical cryogenic nitrogen stripping absorption curve was explained in detail. Then, the evaluation standard system of low-temperature nitrogen adsorption in shale reservoir microscopic pore structure was developed. Engineering practice demonstrated its feasibility, and the study gives reference to the evaluation of shale and coal reservoir pore structure.