Abstract: Accurate identification and classification of shale lithofacies are of great significance for shale oil and gas exploration and development. Based on the grayscale facies model, this paper establishes the intrinsic relationships between absolute grayscale and mineral composition, as well as between relative amplitude and rock fabric, for the shales of the Shahejie Formation in the Dongying Depression. On this basis, a quantitative identification of shale lithofacies and laminae development degree is conducted. The results indicate that high grayscale generally corresponds to calcareous shale, whereas low grayscale tends to indicate mixed shale. High relative amplitude values suggest laminated shale, while low relative amplitude values suggest massive shale. The shales from the lower submember of the third member and the upper submember of the fourth member of the Shahejie Formation in the Dongying Depression are classified into four lithofacies: massive mixed shale, laminated mixed shale, massive calcareous shale, and laminated calcareous shale. Core analysis from Well A reveals that the shales in this interval consist of rapid alternations and stacks of the four lithofacies, characterized by thin single-layer thickness and rapid facies changes. This fully reflects the control of high-frequency paleoclimatic fluctuations on sedimentary processes in continental lacustrine basins, and confirms the validity and applicability of the grayscale facies analysis method for the high-resolution characterization of high-frequency sedimentary sequences in lacustrine shales.