Characteristic of shale reservoir is important to the occurrences of shale gas, gas content and the exploitation. The lacustrine shale in the oil window is quite different from marine shale. This study use quantities of testing data from cores and outcrops to analyze the reservoir characteristics in Lacustrine Shale of Middle Jurassic, North Qaidam Basin. Measures such as core observation, geochemical analysis, XRD-mineral composition analysis, low temperature nitrogen adsorption, FE-SEM and methane isothermal adsorption were used to research reservoir characteristics about rock types, geochemical characteristics, mineral compositional, micro pore structure and gas-bearing properties of the samples from the study area. Compared with marine shale, shale in the study area has the characteristics of “ two high, two low, two types”, high organic matter and clay mineral contents, low thermal maturity and brittle mineral contents, organic matter type are mainly in type II and type III. Low thermal maturity lead to low development of organic pores in the samples, dissolution and mineral transformation are the main factors that contribute to secondary pores. Different from marine shale, high organic matter contents and low thermal maturity lead to liquid hydrocarbons and high soluble organic matter contents, which influence the pore structure and the occurrences of shale gas of the samples, shale samples in the study area have the character that the result of isothermal adsorption have negative linear correction with surface area. The study of the characteristics of high abundance and low thermal stage lacustrine shale provides geological evidence for shale gas exploration and development, and improve the geological theories.