Abstract: There is distinctive heterogeneity in the deposition of lacustrine source rocks.The occurrence of high-quality lacustrine source rocks with rich-organic matter plays an important role in controlling the formation of large oil fields.It has been widely concerned about the mechanism forming rich-organic matter in lacustrine source rock and has achieved significant advance.The deposition of high-quality source rocks has close relationships with the variation of the capacities of lacustrine basins during their evolution,paleolacustrine physicochemical properties,nutrition origin of paleo-productivity,periodic variation of climate and so on.In order to study the formation mechanism of high-quality source rocks,we should try to find out the dependence relations between organic compounds and inorganic elements in sedimentary rhythms in rich-organic matter strata,analyse the coupling relation between cyclicity and incident during geologic succession,inquire into the inherent connection among geologic environment,biogenetic derivation and the formation of rich-organic matter strata.