The Neoproterozoic Xiamaling Formation in the Yanliao depression consists mainly of black-gray shale, yellowish green shale, silty mudstone and cherts. In the black-gray shale, laminar and thin-bedded cherts are widely distributed. Samples systemically collected from the Xiamaling section in Beijing and Xiahuayuan section in Hebei Province are analyzed with the X-ray fluorescence spectrum and analysis of pyrolysis (Rock-Eval) instrument. The results shows that the content of SiO2 in the organic -rich layers ranges from 69. 63% to 91. 09%, higher than in the normal mudstone, and is in direct proportion to the total organic carbon (TOC), but in inverse proportion to the contents of TiO2, which is typical of terrigenous component. The elements of Pb, Zn, P, Co, Ni and V, which are related to hydrothermal venting on the seafloor, and are rich in the organic-rich sediments,and in direct proportion to TOC. The ratio of Ba/Sr in the organic-rich sediments ranges from 5. 6 to 31. 8, which suggests that hydrothermal venting on the seafloor was strong. In the Xiamaling section, laminar and thin-bedded cherts in shale increase in volume gradually from Qb1x3 to upper strata, along with a rapid increase in the content of TOC. The geology and geochemistry indicate that the basin was in strong extension and depression during the formation of the organic-rich sediments of the Xiamaling formation and hydrothermal venting followed with tectonism. Hydrothermal venting on the seafloor can supply nutrition for thermophile microorganism blooming in the area of hot water, and result in the formation of anoxia in bottom water beneficial for the preservation of organic matter.