The Ganzi- Litang ophiolite mélange belt, which is located in the eastern margin of the ‘Three- River’ island- arc basin in southwest of China, is an important window of studying the development and evolution of the Tethys Ocean. This paper carried out a geochemcial investigation on the Jiaokuolongwa siliceous rocks in the middle part of the Ganzi- Litang Ophiolite Mélange Belt. Geochemical analysis shows that the siliceous rocks have SiO2 content of 88.19%~94.57%, Al2O3 of 1.60%~5.33%, TiO2 of 0.05%~0. 19%, (Ce/Ce*)SN ratios of 0.63~1.77 and (La/Ce)SN ratios of 0.35~1.11, generally reflecting the influence of the terrigenous components. The trace element characteristics (V and V/Y) are similar to that of the siliceous rocks in ocean basins, suggesting that the Jiaokuolongwa siliceous rocks were probably formed in a contintental rifting basin, which was affected by terrigenous materials and relatively far away from the continental margin. A large number of late Paleozoic conodonts and radiolarian fossils have been found in the siliceous rocks through fossil identification, indicating that the Zhongzan Block had gradually split from the Yangtze Plate during the middle- late Devonian, accompanied by the formation of the rifting basin in the western margin.