Abstract: Based on the systematic geological survey and sedimentology study of the Longmaxi Formation.in the large area of Yanyuan Basin and the detailed geochemical analysis on the core of CYD2 well drilled in its southern margin, an organic matter enrichment model of the Early Silurian Longmaxi Formation.is proposed.This model gives a good explanation for the mechanism of organic matter accumulation under several influences, and the well understanding of this mechanism will provide a good basis for further high-quality source rock evaluation of shale gas in this area.In this study, the influences including paleo-redox environment, paleo-hydrological conditions, hydrothermal influence, and the factors that affect organic matter enrichment are all discussed.The high-quality source rocks are developed at the bottom(L1~L3)of Longmaxi Formation.in Yanyuan area.It has undergone an evolutionary process from the vulcanization environment with high retention in the early stage(L1)to the open and oxidic environment in the late stage(L5).In the early Silurian, the ancient oceans were strongly influenced by hydrothermal activities evidenced by the obvious LREE enrichment, slight Ce loss and significant Eu enrichment.The early tectonic evolution of the Kangdian Oldland resulted in the intense hydrothermal activities and crustal differential uplifts.It controlled the Paleo-redox condition of seawater and the extend of basin limitation of Yanyuan area during the Early Silurian.The early tectonic evolution of the Kangdian Oldland, together with the continuous rise of sea level, controlled the distribution of ancient marine environment and high-quality source rocks during the Longmaxi period of Silurian in the Yanyuan area.