Abstract: During mapping in the west of Manzhouli, Inner Mongolia near the China-Mongolia border from 2006 to 2008, the Middle Jurassic fossils were collected from the pale yellowish gray pelitic siltstone, which had been originally assigned to the Yiliekede formation in the 1:200 000 regional surveys. Those include plant fossils of Sphenobaiera angustiloba and Schizoneura, as well as Conchostraca fossils of Euestheria Ziliuingensis and E. haifanggouensis. Based on stratigraphic correlation and paleontological characteristics, the clastic rock in the lower part of the series is separated form the volcanic rocks and re-determined as the Middle Jurassic Wanbao formation.