Organic-rich shale deposited in a marine-continental transitional facies was well developed in the upper Yangtze area during the Late Permian. It is considered to contain a large amount of shale hydrocarbon resources. This paper takes the Upper Permian Longtan shale in the central Guizhou uplift as an example to characterize the transitional shale reservoir. Based on organic geochemistry data, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) observation, the geochemic