The Ganzi- Litang ophiolite melange belt, which is an important part of the ‘Three- River’ orogenic belt in southwest of China, had experienced the evolution of paleo- tethys and formed one complete trench- arc- basin system. This study firstly reports the discovery of Dasenlongwa petrofabric ocean island rock association occurring in the Ganzi- Litang ophiolite melange belt. Detailed petrology, geochemistry and geochronology study shows that the ocean island rock is composed of pillow basalt, limestone and siliceous, and the basalt has SiO2 of 44.18% ~ 48.82% and high TiO2 of 2.71%~3.02%. The rock is characterized by a total REE content of 141.03×10-6~164.94×10-6, enrichment of LREE relative to HREE, relative enrichment of Rb, Th and U, and depletion of Ba, K and Sr, no distinct anomalies of Nb and Ta. Its REE patterns and the trace element spider diagram are similar to that of typical OIB. Paleontological fossil shows that the sedimentary time of this oceanic island rock is Permian. The SHRIMP II U- Pb dating of zircon from the pillow basalt yields an age of the middle Permian. This research suggests that the Ganzi- Litang oceanic basin had been mature at least in early Permian.