The Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation is one of the main targets for shale gas exploration in southern China. In this paper, the authors studied the thickness and burial depth of the black shale in Yanzikou area of northwestern Guizhou and its key features of shale gas accumulation such as lithofacies characteristics, mineral composition, total organic carbon content, thermal maturity, storage space and physical properties.The results are as follows:① The thickness of the Wufeng Formation can reach 20 m in western Yile area, while that of the Longmaxi Formation gradually increases from Qianzhong uplift northward, and its maximum thickness is over 250 m in Dingmu'ao-Daping area; ② Effective source rocks are mainly distributed in the lower part of Wufeng Formation and Longmaxi Formation, consisting of clay shale, silty shale and calcareous shale. They are mainly composed of clay minerals, quartz and carbonate minerals with high rock brittleness index (47.3%~76.8%), showing good fracturing ability; ③ Fractures, dissolved pores, intergranular pores, and intercrystalline pores can be identified by SEM, among which dissolved pores and fractures are the main reservoir space. The reservoir has high porosity and shows a good correlation between the BET(13.4~24.9 m²/g) and the total organic carbon content; ④ Geochemical analysis shows that the organic-rich shale section has good types of organic matter, with high organic carbon content (2.56% on average) and organic matter maturity (R_o=2.5%). According to comprehensive research, the north of Yanzikou area and the Gulin-Xuyong border area in southeastern Sichuan is a fairly favorable exploration potential area for Wufeng-Longmaxi shale gas.