Abstract: The present paper restudies the conodonts of Cambrian-Ordovician boundary from Tangshan-Lulong area, Hebei province. An evolutionary sequence of Eoconodontus notchpeakensis through Cordylodus primitivus, C.proavus, C. caboti, C. intermedius to C. angulatus is recognized here. Several proposals for the Cambrian- Ordovician boundary based on the evolution of Cordylodus are also discussed in this paper.