Abstract: Millimeter-scale fine evaluation of shale reservoir performance and oil-bearing property is of great significance for studying the enrichment characteristics of shale oil. This study targets at the medium to high maturity shale in Member 1 of Qingshankou Formation in Gulong sag of Songliao Basin. A series of analytical experiments were carried out, including micro-X-ray fluorescence spectroscopy, rock thin section observation, low-temperature nitrogen adsorption, high-pressure mercury injection, rock pyrolysis, as well as measurement of total organic carbon content. The results show that calcite+clay mineral lamina, clay mineral lamina, calcite lamina, felsic lamina, clay mineral layer, pyrite layer, and dolomite+clay mineral layer are mainly developed in the laminated and layered shale in key exploration sections of the study area. The combination of clay minerals and organic matter can always form organic-clay complexes, and the interaction between the both results in the formation of clay mineral lamina/layer and calcite/dolomite+ clay mineral lamina/layer with larger pore volume and specific surface area, when compared with calcite, felsic, and pyrite lamina/layer. It is verified that clay mineral and organic matter content are the main factors affecting shale reservoir shale reservoir performance and oil-bearing property in the study area. It is suggested that the shale strata rich in organic matter and clay mineral should be the preferred target for exploration.