The Donggou section of Dadianzi Village in Luanping County, northern Hebei Province is the naming section of the Dadianzi Formation by Mr. Wang Si’en in 1990. This formation may be divided in ascending order into four members in the Zhangjiagou section. Abundant conchostracan fossils were found in the Dadianzi Formation of this section, including 7 genera and 47 species. From the base upward, the Conchostracan biostratigraphy of the Dadianzi Formation is divided into five conchostracan zones. Because of the event of drop in temperature and the event of vanish and newborn of conchostracan fauna between the Dabeigou Formation and Dadianzi Formation, the boundary of continental Jurassic-Cretaceous System is determined in the point between the Dabeigou Formation and Dadianzi Formation.