The Qingshankou Formation was the main source rock in the Sanzhao Depression of the Songliao Basin, with a relatively large thickness of shale. Among them, the first member of the Qingshankou Formation was characterized by semi-deep lake to deep lake sedimentation, with a generally warm and humid climate, and developed shale with relatively large single-layer thickness, which was stably distributed in the Sanzhao Depression. Geochemical analysis of samples showed that the shale of the first member of the Qingshankou Formation had good organic matter type, high organic matter maturity, and great hydrocarbon generation potential, making it the main target layer for shale oil exploration in the Sanzhao Depression. The second and third members of the Qingshankou Formation were mainly characterized by coastal and shallow lake sedimentation, with local development of shale with relatively large hydrocarbon generation potential, indicating the potential for shale oil exploration. Based on the analysis of the sedimentary environment and mineral composition and structural characteristics of the shale in the Qingshankou Formation, it was found that the microscopic pores in the Qingshankou Formation shale oil reservoirs in the Sanzhao Depression mainly developed five types of storage spaces: intergranular pores between minerals, intragranular dissolution pores, intercrystalline pores of pyrite, organic matter pores, and microfractures. On this basis, through the effective combination of resource sweet spots and engineering sweet spots, and comprehensive analysis and evaluation, it was believed that the deep lake organic-rich feldspathic shale of the Qingshankou Formation was the best sweet spot for shale oil in the Sanzhao Depression, with the greatest exploration potential. The organic-rich laminated clay shale had the second greatest exploration potential, while the laminated shell (calcium-rich) shale and dolomitic shale had relatively the poorest exploration potential.