The rapid lithofacies transitions and compositional heterogeneities inherent in lacustrine shale posed significant challenges to accurately characterizing it, thus impeding the optimization of shale oil exploration and extraction. This study employed a multifaceted methodology to address these obstacles, integrating principal component analysis (PCA), K-means clustering, and geochemical trend analysis to precisely identify and characterize nine distinct chemofacies. A comprehensive analysis of petrological characteristics and depositional environments was accomplished by examining core samples, thin sections, scanning electron microscopy (SEM), mineralogical compositions, and total organic carbon (TOC) content. The identification of favorable locations was supported by meticulously considering variables, including TOC, porosity, permeability, and the mineral brittleness index (MBI). This investigation revealed the presence of nine distinct chemofacies within the targeted layer. Specifically, Chemofacies 5, characterized by calcite vein laminations, was identified within Unit 2 parasequence, and Chemofacies 6, enriched with feldspar-quartz mineral laminations, was located within Unit 4 parasequence. Both chemofacies exhibited elevated TOC, enhanced porosity and permeability, and favorable brittleness, qualifying them as ideal sweet spots for shale oil exploration. The insights from this study align with the characteristics of traditionally optimal reservoirs, validate the robustness of the employed methodologies, and carry significant implications for the accurate prediction of terrestrial shale oil sweet spots in future explorations.