The Late Mesozoic was an important period in the subduction of the Paleo- Pacific plate and the development of the East Asian continental margin accompanied by intense magmatic activity in the South China block. In this paper, the sandstone samples from the Shimentan Formation (2031~2097 m) and the Mingyuefeng Formation (1755~1806 m), closely adjoining the Mesozoic granite basement, were selected from the well FZ211 in Lishui sag, East China Sea, for analysis of detrital zircon U- Pb isotopes and trace elements. We obtained the result of two major magmatic events that activated in the Jurassic (180~160 Ma) and in the Cretaceous (140~80 Ma), respectively, within which the age range of 120~80 Ma was a major period. The dated detrital zircons from the two magmatic episodes are characterized by low temperature (605~792℃), fluid- mobile elements U, Th, and LREE enrichment, and depletion in high field- strength elements Nb, Ta, Ti, and HREE. They were formed in a typical magmatic arc environment. Compared with oceanic- type zircon, the U/Yb ratios (0. 1~5. 1) of dated igneous zircons fall in the range of continental- type zircon, but with a transitional trend towards the type of oceanic zircon in the Cretaceous. The Yushan uplift from the East China Sea, as a sediment source for the dated samples, should be an important part of the Late Mesozoic magmatic arc, with strong subduction and magmatic activity in the period of 120~80 Ma. The Yushan magmatic arc, if connected with units of the Fuzhou forearc basin and SW Japan- Taiwan accretionary complexes, constitutes an architecture of Late Mesozoic continental margin of East China Sea, that was controlled by the subduction of Paleo- Pacific slab rollback.