In this paper, based on a study of mineral chemistry of mantle peridotites as well as petrochemistry and geochemistry of mantle peridotitses, basalts, gabbros from Zedang ophiolite, combined with previous research of chronology and tectonic setting in study area, we discuss the origin and evolution of Zedang ophiolite. ①Based on a resrarch of Fo values of olivine, En and Mg# values of clinopyroxene and orthopyroxene, contents of Al2O3 of clinopyroxene and orthopyroxene, Mg# and Cr# values of spinel, we found that Zedang mantle peridotites originated from depleted mantle source in a MOR(mid ocean ridge) environment, then was modied by later stage melts and uids in a SSZ (Suprasubduction Zone) setting, and that the molten degree of harzburgites is higher than lherzolites.②Based on a resrarch of petrochemistry and geochemistry of mantle peridotitses, we found the contents of most major elements and trace elements in mantle peridotites are lower than that in primitive mantle, the distribution patterns of trace elements well coincide with abyssal peridotites, which proved again mantle peridotitses originated from depleted mantle source in a MOR environment.③We found that gabbros from Zedang ophiolite had the feature of N MORB (Normal type Mid Ocean Ridge Basalts) and originated from a source region which was much more depleted than N MORB, the gabbros also had the feature of IAT(Island Arc Tholeiites) and probably ascribe it modied in a SSZ setting.④There are two types basalts in Zedang ophiolite, N MORB and E MORB(Enriched type Mid Ocean Ridge Basalts), because the source region might have the feature of inhomogeneity, which include enriched magma. N MORB type basalts also have the feature of IAT, indicating them modied in a SSZ setting later, whereas E MORB type basalts not have the feature of IAT. ⑤Combined with previous research of chronology and tectonic setting in study area, Zedang ophiolite originated from depleted and inhomogeneous mantle source in a MOR environment in c. 170Ma, then was modified in a fore arc setting in c. 150 Ma.