Abstract: According to maceral constituent of organic matter, hydrocarbon-generating potential, sedimentary facies, geochemistry facies and atomic ratio of kerogen element etc., the organic facies is divided into four types:Lipid hydrogen-rich face, Lipid-vitrum hydrogen-rich face, Lipid-vitrum hydrogen-poor face and vitrinite hydrogen-poor face; Based on the above-mentioned data, organic facies maps of Eocene Series, Oligocene Series and Miocene Series were drawn. This research have been taking an important role in petroleum exploration and development in Xihu Sag.