Some well-preserved fossil dinoflagellate cysts were found from a lacustrine facies with salt deposition in the Shulu Sag of Hebei Province, China. The diversity and abundance of the assemblage were both low, which indicated a paleoenvironment of brackish water. The main species could be found from the First Member of the Shahejie Formation in Coastal Bohai Region of China, which suggested a geological age of Oligocene. Fossil dinoflagellates showed significance in non-marine facies for recovery of paleoenvironment and regionally stratigraphic correlation. Brackish dinoflagellates are constructive to the formation of salt rocks, and dinoflagellate cysts in salt lakes are easy to be preserved as fossils.