Abstract: Using zircon U-Pb dating as the main analysis method, the age of the pre-Cenozoic sedimentary basement was determined and the sediment source in the sag during the fault depression was traced in the Jiaojiang Sag, East China Sea Shelf Basin. The pre-Cenozoic basement of Jiaojiang Sag is dominated by magmatic rocks. The age distribution of detrital zircons is complex, with the main peak age of 227 Ma, mainly formed in the late Indosinian period. The formation environment belongs to the oceanic island arc environment, which is consistent with the existing magmatic records of Lishui East Sub-Sag and Yushandang Low Uplift. The clastic zircons of the Paleocene Mingyuefeng Formation have typical magmatic characteristics, with the main zircon peak ages ranging from 140 Ma to 90 Ma. The formation environment belongs to a continental margin environment. The Paleocene provenance of Jiaojiang Sag is relatively single, which is comparable to Lishui Eastern Sub-Sag. The Yandang Low Uplift in the east of Jiaojiang Sag provides a continuous provenance supply during the Paleocene fault depression.