The Fuchuan ophiolite is preserved well in the Jiangnan orogen of South China. In Fuchuan area, ophiolite is composed of the largest mantle peridotite massif in the orogen, cumulated rocks, pillow lavas and some ribbon cherts. The mantle peridotite massif includes major massive harzburgite with high-Cr# value (54 to 60) spinels and U-shaped REE patterns. The cumulated rocks are composed of dunite, wehrlite and gabbro, thus being of the DPG type. All these features are consistent with those of the Izu-Bonin-Mariana peridotites, indicating that the Fuchuan ophiolite was formed in the supra-subduction zone (SSZ). The SHRIMP U-Pb ages of the co-magmatic zircon domains from gabbro that intruded the h arzburgite and the wehrlite are 848±12Ma (n=7, MSWD=1.9) and 827±9Ma (n=12, MSWD=1.4), respectively. The SSZ-type ophiolite and its ages suggest that the subduction of the ancient ocean between the Yangtze terrain and the Cathaysian (called “Jiangnan Ocean") terrain started before Neoproterozoic. It is inferred that the tectonic transform of the Jiangnan Ocean from spreading to subduction began before Neoproterozoic in southern Anhui Province, and the Yangtze terrain and the Cathaysian terrain started to collide before 848 Ma.