Abstract: The continental lacustrine shale is developed in Nenjiang Formation of Songliao Basin, and characterized with wide distribution area, good quality of source rocks and large-scale potential shale oil resources. Previous studies mainly focused on the medium-high mature shale reservoirs of Qingshankou Formation, and rare attention is paid on the medium-low mature lacustrine shale in Nenjiang Formation. Based on whole-rock mineral analysis, organic geochemical analysis, as well as test data of field emission scanning electron microscopy and nitrogen adsorption, in combination with the regional tectonic background and sedimentary characteristics, the paper comprehensively analyzes the distribution of shale and the characteristics of source rocks, shale oil content and reservoir property of Nenjiang Formation, and discovers the geological characteristics and resource potential of shale oil in Nenjiang Formation. The results show that the shale is widely developed in Member 1 and 2 of Nenjiang Formation, with large thickness and stable distribution. Vertically, there are three sets of shale reservoirs with high organic matter in Nenjiang Formation, dominated by the organic matter of Type I and II₁ in the medium-low mature stage. The nano-scale reservoir space of shale is dominated by intergranular pores, intragranular pores and pyrite intercrystalline pores, and the pore size is mainly distributed in the range of 64 nm to 128 nm. The paleoenvironment provides a material basis for the development of organic matter, and the enrichment of shale oil is jointly controlled by the coupling of high quality source rocks and multi-type nano-level reservoir space. The comprehensive evaluation shows that the best sweet spots are developed in Member 2 of Nenjiang Formation, followed by the middle section of Member 1 of Nenjiang Formation. The oil resources are preliminarily estimated to be more than 100×10⁸t. Well NY1H in Nenjiang Formation was deployed and drilled in 2021 by Daqing Oilfield Company Limited, with a cumulative oil production of 2 160 t, achieving stable production of medium-low mature shale oil in Nenjiang Formation, which confirmed that Nenjiang Formation has a good resource base of shale oil and utilization potential.