Abstract: The Chengjiang Formation is one of the earliest stratigraphic units above the Jinning unconformity.Determining the sources is of great significance for the understanding of the early crustal evolution in the western Yangtze Block.U-Pb dating and Lu-Hf isotopic composition studies were carried out on the detrital zircons from the Lower Chengjiang Formation in the Dongchuan area of the western Yangtze Block.The U-Pb ages of the zircons are clustered at 780~900 Ma, ~1000 Ma and~1800 Ma respectively, and the weighted mean age of the youngest group is 801±5 Ma(MSWD=2.4, n=9), which is consistent with the volcanic age of the Lower Chengjiang Formation.Thus, it is further confirmed that the lower age of the Chengjiang Formation should be limited at~800 Ma.Combined with the U-Pb age and Hf isotopic composition, zircon morphology and paleogeography, it is believed that the detritus was largely sourced from the widely distributed Neoproterozoic magmatic rock in the western Yangtze Block, and a small part from the recycled materials of the Dongchuan Group.Regional comparison of the early Nanhua strata of the Yangtze Block indicates that the western and northern margins of the Yangtze Block show different crustal evolution history.The provenance differences of the Chengjiang Formation in different regions of the western margin of the Yangtze are closely related to regional tectonic activities.