Abstract: In 2019, the Changqing Oilfield deployed 2 horizontal wells, Chengye-1 and Chengye-2 to carry out risk exploration research tests for shale oil in thick shale interlayered with thin siltstone and fine-sandstone layers (Class II shale oil) in the 73 member of the Yanchang Formation (the Chang 73 member) in the Ordos Basin. High-production oil flows of 121.38 t/d in Well Chengye-1 and 108.38 t/d in Well Chengye-2 have been obtained, which significantly boosts the exploration progress of Class II shale oil. In this paper, cores, thin sections, well loggings and geochemical data from the two horizontal wells, Chengye-1 and Chengye-2, and the pilot well of Well Chengye-1 have been used to study the reservoir conditions and resource potential of Class II shale oil reservoirs in the Chang 73 member. The results show that the reservoir type penetrated by horizontal sections of the two horizontal wells is mainly thick shale interlayered with several thin siltstone and fine-sandstone layers. Thickness of the single layer sand body is 1?5 m. Lateral extension length of single sand body in the horizontal direction is generally in the range 25?50 m and the lateral width of sand bodies is 100?300 m. The distribution area of the single sand body is relatively small. The reservoir types are intergranular pores, dissolution pores, pores, inter-crystalline pores, organic pores and fractures. The intergranular pore radius is concentrated in the range 0.1?3 μm with the maximum of 21 μm. In reservoirs penetrated by pilot sections and horizontal sections, high-conductive fractures are well developed and distributed in an E-W orientation. The porosity of the sandstone reservoirs is 6?12%, and permeability is generally less than 0.3 mD. Shale reservoirs offer poor reservoir performance, with porosity less than 2% and permeability less than 0.01 mD. Using methods such as rock pyrolysis, petroleum ether extraction and dichloromethane extraction, movable shale oil resources in shale and sandstone in the Chang 73 member within a 220 km2 area of the Chengye well block have been evaluated. Preliminary evaluation results indicate resources of (0.692?0.783)×108 t. The distribution area of Class II shale oil in the Chang 73 member in the Ordos Basin is about 1.5×104 km2, and the prospective resources of Class II shale oil in the Chang 73 member are 33×108 t.