The Meirenfeng Formation in the Yangtze River sag of the East China Sea basin is one of the important stratigraphic units in the Paleogene. However, due to the lack of accurate paleontological fossil records, the sedimentary age and regional stratigraphic correlation of the Meirenfeng Formation have remained unresolved for a long time. In this paper, the LA- ICP- MS dating method is used to carry out zircon U- Pb isotopic dating of the two sets of tuff interlayer on the top of the Meirenfeng Formation exposed in well CJ- 2 of the Yangtze River sag. The results show that the two tuff samples from the top of the Meirenfeng Formation were formed at 61. 0±0. 87 Ma and 62. 25±0. 92 Ma, respectively, which proves that the sedimentary age of this group belongs to the Early Paleocene and corresponds to the Lower Paleocene Yueguifeng Formation in the Lishui- Jiaojiang sag. According to source rock evaluation, the Meirenfeng Formation has developed relatively good source rocks, with medium to good organic matter abundance, and the organic matter type is type III. Based on the fine analysis of seismic profiles, the Meirenfeng Formation in the Yangtze depression can be continuously traced to the East Zhejiang depression. The Paleocene series developed on a large scale in the East Zhejiang depression, with a residual thickness of 800~2000 m. During the Paleocene, a large- scale extensional rift occurred in the East Zhejiang depression, forming a large- scale NNE- oriented rift zone. The Meirenfeng Formation is a set of potenial source rock formations. This is the first time that a high- precision age has been obtained in the Meirenfeng Formation in the Yangtze River sag of the East China Sea basin. It not only determines the sedimentary age of the Meirenfeng Formation, but also serves as the basis for the division and comparison of the Paleocene regional strata in the East China Sea basin, the reconstruction of basin paleogeography, structural evolution, oil and gas exploration, and resource evaluation, etc. provide a new geological basis.