Abstract: Petrochemical and geochemical data show that the Paleoarchean Chentaigou ophiolite, composed of chlorite talc-schist, serpentinite (peridotite), amphibolit (tholeiite) and quartzite, has the essential characteristics of ophiolite suite, probably to be the relics of Paleoarchean oceanic crust. The Chentaigou ophiolite is characterized by poor silicon and alkali and low titanium, but rich iron and magnesium, with low total REE. Analysis on trace elements indicates that the basalt in the ophiolite is enriched in large ion lithophile elements(LILEs, such as K, Rb and Ba), whereas depleted in high field strength elements (HFSEs, such as Nb and Hf), with the characteristics of island-arc volcanic rocks. The chondrite-normalized REE distribution patterns of the ophiolite show mostly flat curves. It is concluded that the Chentaigou ophiolite probably occurred and developed in an island arc environment.