Abstract: In the lake basins of China,the chert is a very rare rock type.So far,there are not special studies and reports on chens in lacustrine strata at home.In this paper,it is first advanced that laminated chens exist in the Paleogene lacustrine strata of west Liaohe Depression.And based on geologic setting conditions and sedimentary and geochemical characteristics,their genetic mechanism is approached preliminarily.