Late Devonian-Early Carboniferous deposits in the Tarim Basin are divided into the Donghetang, Ganmulike and Bachu formations, in which abundant and well-preserved spores, conodonts and fish fossils have been found. Based on the spores assigned to the Apiculiretusis pora hunanensis-Ancyrospora furcula (HF) spore zone recognized in the Donghetang Formation of borehole Cao-2, which is of marked Late Devonian palynofloral characters, and the fish remains assigned to Placoderm from the Ganmulike Formation of borehole TZ45, the Donghetang and Ganmulike Formations are believed to be Late Devonian in age. The conodont fauna from the upper part of the Bachu Formation display Devonian-Carboriferous transitional characters and the spores from the lower part of the formation can be correlated with the basal Carboniferous spore zone of western Europe; so it is suggested that the Bachu Formation be Early Carboniferous in age and that the Devonian-Carboniferous boundary be between the Ganmulike and Bachu Formations.