Based on the measured element content of outcrop samples and drilling cutting samples of the Ordovician Wufeng Formation shale and Silurian Longmaxi Formation shale, chemical elements and oxide-geochemistry features of the shale in the Jiaoshiba area were researched. The results show that the shale formations have a higher SiO2 content overall, and the chemical indexes of alteration (CIA) are between 55 and 77 which indicates the shale developed under a warmhumid climate. The elements characteristics of different shale samples are significantly different, which show a huge difference in the quality of shale. The excess SiO2 content of the drilling cutting samples are very low in the upper of Longmaxi shale and the value of U/Th is less than 0.75, which indicates that the shale formed under an energetic and oxygen-enriched environment, and the organic matter is difficult to be saved, so the shale quality is poor. The excess SiO2 content of the drilling cutting samples is between 6.6% and 12.9% in the lower of Longmaxi shale and the value of U/Th is between 0.75 and 1.25, which indicates that the shale formed under an oxygen-poor and comparatively calm-water environment, so the quality of shale which is characterized by high organic matter content and good compressibility is good. The excess SiO2 content of the outcrop samples of the Wufeng Formation shale is between 11% and 24% and the value of U/Th is between 0.76 and 1.34, which indicates that the shale formed under an oxygen-poor or anaerobic environment. The organic matter content is so high that it is easy for the shale to develop natural fracture or to be fractured. So the shale quality is excellent.