As the distribution of Lamprotula fauna was controlled by climate and environment，the study on Lamprotula fauna might reconstruct the palaeoenvironment at that time. 13 species of the Holocene Unionidae fossils were found in Baiyangdian area of Hebei Province，which belonged to Lamprotula-Cuneopsis-Unio assemblage named as Baiyangdian Lamprotula fauna. Compared that fauna with the modern Lamprotula fauna living in Taihu Lake，Poyang Lake，Dongting Lake and their surrounding water in the Yangtze River downstream watersheds，and the Middle Holocene Lamprotula fauna found in Wangyin of Shandong Province and Xishuipo of Henan Province，they all belonged to the China-India Subrealm of Oriental Realm and in lacustrine environment in subtropical humid climate zone，although Baiyangdian Lamprotula fauna contained certain similar characteristics of the mentioned faunas with low diversity in assemblage during the early Middle Holocene. It was indicated that the north boundary of the North Subtropics and the Oriental Realm was located in Beijing-Tianjin area to the north of Baiyangdian，and extended westwards to Hetao area of Inner Mongolia Autonomous Region.