Abstract: Based on the discovery of condont fossils near the boundary between Cambrian and Ordovician systems on the Jiangshan-Yangligang Section in Zhejiang Province, three fossil assembledges Zone are defined in this paper as. 1. Proconodontus muelleri, 2. Cordylodus proavus, 3.Utahconus-Monocostodus sevierensis. The biostratigraphic boundary between Cambrian and Ordovician systems is placed between the assembledges Zone of Cor-dylodus proavus and Utahconus-Monocostodus sevierensis. The defined groups (assembledges) of conodonts can be compared not only with those both at home and sbroad, but also with macro-fossil assembledges(groups). Furthermore, the defined boundary is coincided with those made by international working group on the boundary of Cambrian-Ordovician systems which was decided by votes.