The Dingqing ophiolite is located in the eastern segment of the Bangongco- Nujiang suture zone and is divided into the eastern and western rock mass. However, there has been no chronological report on mafic rocks in the western ophiolite of the Dingqing. The geological mapping of the western ophiolite shows that ophiolite is mainly composed of harzburgite, dunite, diabase, basalt and gabbro. Basalt, gabbro and diabase outcrop mainly in the Zongbai area, with basalt and diabase in tectonic contact with the Lower Jurassic sedimentary rocks, and the gabbro dykes dipping into the Lower Jurassic sedimentary rocks. Lithogeochemical study indicates that basalt and gabbro are both alkaline rocks, and basalts have the characteristics of rare earth and trace elements of typical oceanic island basalts, suggesting that it formed in the ocean island environment associated with mantle plumes. The dating for zircons selected from basaltic tuff yielded a U- Pb age of 198. 7±3. 8 Ma, indicating the Early Jurassic. Gabbro contains lower contents of rare earth and trace elements than typical oceanic island basalt, but its REE and trace elements have the characteristics of OIB. Compared with the typical OIB, gabbro is enriched in HREE to a certian extent. Zircon from gabbro has a U- Pb age of 164. 3±2. 6 Ma, suggesting that gabbro formed in the continental marginal rift environment and was affected jointly by and the upwelling asthenosphere and enriched melting of LVZ integration at the bottom of the lithosphere. The composition of diabase indicates that it belongs to tholeiitic basalt, and the REE and trace element diagrams of diabase show the characteristics of N- MORB and E- MORB. Zircon U- Pb age of the diabase is 114. 2±1. 3 Ma, suggesting that diabase formed later than basalt. Combined with regional geology, it is believed that diabase formed in the post- arc expansion ridge environment affected by the mantle plume. This study provides new chronological and petrological evidence for the formation and evolution of Dingqing ophiolite.