Abstract: The Fengcheng Formation (P₁f) is the main source rock in the northwestern Junggar Basin and is the key horizon for shale oil exploration and development in the future. Previous studies mainly focused on the sedimentary environment, petrology, reservoir pore structure and physical properties of P₁f, but relevant research on the microscopic occurrence characteristics of shale oil is relatively weak. To reveal the oil content and micro-occurrence characteristics of shale oil in different lithofacies of P₁f in the northwestern Junggar Basin, 81 mud/shale samples from 4 wells to effectively avoid the errors and accidents caused by single experiments through the joint application of field emission scanning electron microscope (FE-SEM), nuclear magnetic resonance (NMR) and stepwise extraction experiments. The occurrence state across six lithofacies of shale oil was systematically characterized in the study area. The experimental results show that the combined application of SEM and NMR methods can be used to effectively identify shale oil occurrence states. Free oil exhibits a linear distribution of T₂ > 2 ms, T₁/T₂ ≈ 10, mainly residing in pores and microfractures >50 nm. Adsorbed oil shows a zonal distribution of T₂ < 2 ms and T₁/T₂ ≈ 100, occurring as oil films on clay mineral surfaces and within pyrite aggregates. These findings can be used to provide technical support for distinguishing sweet spot shale oil. The integrated application of the NMR method and three-step light/heavy hydrocarbon extraction, combined with the developmental characteristics of shale oil reservoir types across different lithofacies, clearly indicates that the calcareous mudstone/shale is the most favorable lithofacies of P₁f, in the study area, followed by dolomitic mudstone/shale (with the strongest oil capacity) and the dolomitic tuff. Among these, the third member of P₁f in the area of Well Hashenxie 1 exhibits high oil content (TOC 1.5%–5.13%, S₁ 1.2–4.02 mg/g, free oil accounting for 20%–40%), high porosity (porosity 4.2%–6.58%, with developed intragranular pores, intergranular pores and micro-fractures), high brittleness (brittle mineral content 55%–71%, Leeb hardness 450–650, good compressibility) and other characteristics, making it the most favorable target section. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202506040146.