Abstract: Shale oil in Biyang sag is mainly distributed in larger pores and fractures by means of adsorbed oil and free oil. The free oil is mainly distributed in interlayer fractures, structural fractures and larger matrix pores, and its distribution is mainly affected by matrix pores and fractures. While the adsorbed oil mainly occurs on the surface of organic matter and clay mineral particles. By carrying out related experiments on shale movable oil, the evaluation index and limit of shale movable oil were established, and the influencing factors of movable oil were defined. The experiment results showed that the ratio of free hydrocarbon(S1) to organic carbon content was 60 mg/g, the ratio of chloroform asphalt ‘A' to TOC was 0.2, and the limit of movable throttle of shale was set when the burial depth was 2 000 m. The degree of movable oil enrichment is mainly related to depth, organic carbon content, porosity and mineral content such as quartz, feldspar and clay.