Late Paleozoic marine (Oceanic island) basalt in western Guangxi was discovered in Youjiang Basin at the end of last century, which has also been reported recently. The basalt of ocean basin and ocean ridge is the precondition to judge the existence of ocean island.Results:Through 1∶50000 regional geological survey and profile study, The Lower Carboniferous Bada Formation (C1b) in the Bada and Lihu areas of southeast Yunnan is mainly composed of grayish black and grayish white thin bedded siliceous rocks, radiolarian siliceous rocks, spongy spicule siliceous rocks, basalt with tuff, argillaceous limestone and mudstone, with typical ocean basin sedimentary formation composed of siliceous rocks basalt limestone mudstone, including conodonts, trilobites, etc.Conclusions: The basic ultrabasic lavas erupted on the Tapi Formation have obvious characteristics of oceanic tholeiite. Therefore, the division and correlation of the Bada Formation provides an important basis for the study of the Late Paleozoic Middle Triassic island ocean basin environment in the Youjiang Basin, and is of great scientific significance for the study of the splicing process between the Cathaysian orogenic belt and the Yangtze Block.