Objectives:The fragmentary ophiolite fragments distributed in the Jiangnan orogenic belt have important geological significance for constraining the tectonic evolution of the Jiangnan orogen. Combined with petrological study and SHRIMP UPb zircon ages of the northeastern Jiangxi ophiolites and the Zhangcun Group, we briefly discuss the tectonic evolution of the Jiangnan orogen. Methods: Based on the field work, through the microscope observation, the whole rock chemical analysis, the the O isotopic analysis and SHRIMP UPb zircon dating of the Zhangshudun ophiolite and tuffaceous phyllite of of the Zhangcun Group. Results: The geochemical analyses of mafic—ultramafic rocks in the Zhangshudun ophiolite show that the gabbro yields the MORBlike geochemical composition and the serpentinite is strongly depleted in the trace elements. The SHRIMP O isotope analyses of zircons in gabbro yield homogeneous O isotope (5.12‰ ± 0.62‰，2 ), similar to the O isotope of zircons in mantle (5.3‰ ± 0.3‰). These geochemical characters support that these rocks represent remnants of ancient oceanic crust and upper mantle. SHRIMP U-Pb zircon analyses yields the formation age of 1009 ± 5 Ma (MSWD = 1.15) for the gabbro in the Zhangshudun ophiolite. As the surrounding rocks of the Northeastern Jiangxi ophiolite, the formation age of the Zhangcun Group is constrained by the SHRIMP UPb zircon dating of a tuffaceous phyllite which yields the formation age of 833 ± 10 Ma (MSWD = 1.5). This age suggests the emplacement of Northeastern Jiangxi ophiolite is later than 833 Ma. Conclusions: Combined with the early research, we suggest that the Northeastern Jiangxi ophiolite formed at the midocean ridge environment in lateMesoproterozoic to earlyNeoproterozoic, different from the midNeoproterozoic backarc basin represented by the Fuchuan ophiolite in the south Anhui province. These new data provide new constrains for tectonic evolution of South China.