Abstract：Abundant well-preserved radiolarians were discovered in cherts in the Artengkesi Formation south of Korgan, South Tianshan, Xinjiang. They comprise 21 genera and 46 species, of which eleven are indefinite species and one is indefinite genus. Study indicates that the radiolarian assemblages of two samples are Middle-Late Devonian and Early Carboniferous in age. The discovery of the Middle-Late Devonian radiolarian assemblage enriches the Devonian radiolarian fauna in the Kuqa area and provides fossil evidence for the determination of the age of the Artengkesi Formation. On that basis, combined with previous studies of fossils in this formation, the authors think that this formation is an age-straddling lithostratigraphic unit and should be disintegrated into the lower, Middle and Upper Devonian stratigraphic units. The abyssal sediments containing Early Devonian-Late Carboniferous radiolarian cherts provide stratigraphic evidence for the evolution of the South Tianshan paleo-ocean basin.