Abstract: Cypridea (Pseudocypridina) gigantea of ostracods is regarded as the important member of Late Cretaceous in Junggar basin. It is an ostracod of the mid-late epoch of Late Cretaceous, corresponding to Campania-Maestrichian epoch, widespread in Upper Cretaceous in China. It can be as a marker member of Late Cretaceous for its broad distribution in geography, but short duration in geologic period and well used for strata classification and correlation. From well-developed red layer of Late Cretaceous in Junggar basin, with drier climate, oxidized and evaporated environment, fewer bio-fossils at that time. The existence of ostracod indicates a little fresh and shallow water environment like lake, marsh, pond, river, etc., with low salinity, mostly being river-shallow lake environment in Late Cretaceous of Junggar basin.

Key words: Junggar basin, Cypridea (Pseudocypridina) gigantea, fossil, Late Cretaceous