Using the LA- ICP- MS U- Pb isotope measurement technique, a Hadean zircon was found in the rhyolitic vitreous sintered tuff of the Paleoproterozoic Abudu Formation in Dongchuan Luoxue area, western margin of the Yangtze plate. The zircon has an obvious core- mantle- edge structure. The 207 Pb/ 206 Pb age of the core is 3890±47 Ma. This age is interpreted as magmatic crystallization, and the Th/U ratio is 0. 34. The 207 Pb/ 206 Pb age of the metamorphic edge is 3561±45～3616±55 Ma, Th/U ratio is 0. 07~0. 19. The in- situ Hf isotope measurement of zircon yields 176 Hf/ 177 Hf=0. 280317~0. 280451, ε Hf ( t )=-4. 6~0. 6 (average value is -2. 5), T DM1 =3861~3980 Ma, T DM2 =4036~4106 Ma (average value 4059 Ma). This zircon is the oldest zircon found in the Yangtze block. Its Hf isotope and trace element characteristics indicate that there is 4. 0 Ga crustal hyperplasia in the Yangtze block and recycling of the ancient continental crust. Combined with the data of previous isotope studies, it shows that the Proterozoic in the Dongchuan area on the western margin of the Yangtze may be related to the North China block during this period. This discovery provides an important basis for the Yangtze block to be investigated for the pseudo- continent and Archaean material entities, and also provides important new information for understanding the evolution process of the early continent.