The Yixian Formation is the most important bed for Jehol Biota. A lot of fossils preserved well of Jehol Biota were found in Yixian Formation which recorded the important information of the Jehol Biota evolution. In order to understand and rebuild the living environment of the Jehol Biota, it is necessary to carry out further sedimentary environment studies of Yixian Formation. The aboundant informations of sedimentary environment were recorded in several carbonate interlayers in the Yixian Formation of Western Liaoning. Through the studies of the carbonates, the lost environmental informations of the clastic rock can be obtained. The studies on carbonate and clastic rock provide scientific evidences for rebuilding the palaeoclimate, palaeogeography and palaeoecology of Yixian Jehol Biota of Western Liaoning. Eight lithotypes of carbonates have been identified by studies in the field and laboratory. The environmental analysis has been done by studying the sedimentary characteristics of the carbonate. The field works indicate that the development of the carbonate interlayers has the tendency of increase in terms of the layers and carbonate content to the southern direction of the basin. The palaeoenvironment of the Western Liaoning was dominated by shore-shallow lacustrine facies in Yixian period, and the carbonates mainly deposited in very shallow depressions on the floodplain as well as slight-brackish water in shore-shallow lacustrine environment. When the carbonate deposited, the climate was relatively dry and hot, the lake hydrology tended to close, volcanic activities were frequent and the lacustrine water supply was less than evaporation.