Abstract: The Lucaogou formation in the Jimsar sag is a typical shale oil reservoir, and the “sweet spot” of shale oil reservoir is the main target for oilfield development. The pore structure of the reservoir is the foundation of reservoir research. The pore characteristics of the reservoir of Lucaogou formation in the Jimsar sag are analyzed by using low temperature liquid nitrogen adsorption, high pressure mercury injection, scanning electron microscopy and nuclear magnetic resonance. The results show that the pore types of the Lucaogou formation are mainly nanopores and submicron pores. The diameter of the nanopores is mainly distributed in the range of 10~80 nm，and the submicron pore diameters are mainly distributed in the range of 0.1~0.3 μm. The four methods are compared and the advantages，disadvantages and priorities of the various methods are clearly explained