The Cyathaxonia faunas are widely distributed in the Carboniferous and Permian strata in China. The fauna in China contains 12 families and 40 genera, and can be recognized as three episodes from Early Carboniferous to the end-Permian in terms of their occurrence and composition: 1) Mississippian; 2) Pennsylvanian-Early Permian; 3) Middle Permian-Late Permian. They were relatively abundant in episodes 1 and 2. A decrease of family Antiphyllidae and an increase of family Hapsiphyllidae can be observed from Early Carboniferous to the end-Permian. Two case studies are given to illustrate the bio-facies of the Cyathaxonia faunas, which are from the Mississippian of Baoshan, West Yunnan and the Mississippian of Chaohu, South Anhui. In both areas, Cyathaxonia faunas occur just below the large dissepimented solitary and compound coral assemblages in a continuous sequence in a single section, which implies that the occurrence of these small, non-dissepimented solitary corals is not strictly related with Gondwanan or Peri-gondwanan cold water environment, but might be controlled by such benthic conditions as deeper, mud-rich, quieter, and darker sedimentary environments.Cyathaxonia fauna was first introduced by Hill [1]. In the investigation of rugose corals from Scotland, she recognized three coral assemblages based on the relationships between coral occurrences and sedimentary facies, i.e., the major coral biofacies, in Carboniferous: 1) Cyathaxonia fauna, 2) Caninid-Clisiophyllum Fauna, and 3) Reef-Coral Fauna. The first assemblage is also known as the small, solitary, non-dissepimented coral fauna due to their simple morphological features that characterized all those corals of this fauna. Incidentally, the taxon Cyathaxonia does not necessarily always occur in this fauna.The occurrences of compound colonies of modern corals, especially the coral reefs, are an index of low latitude temperate zone or tropic areas with moderate temperature, indicating a warm and clean seawater environment. The small solitary corals in present sea, however, not only appear in the coral reefs, but also live in various ecological conditions, e.g., deep water or middle latitude regions [2]. The study on the extinct rugose corals and their ecological significance has had a long history among coral experts [3]. There are few arguments over the ecology of the reef building colonial and large solitary rugose corals. But many disagreements remain on the ecology of small solitary non-disepimented rugose corals. These morphologically simple, widely distributed and slowly evolving taxa in the Carboniferous and Permian are of little use in biostratigraphic aspects but bear relatively highly on the paleoecology and paleogeography. Some Chinese researchers hold that the small, solitary, non-dissepimented rugose corals in the Carboniferous and Permian were cold-water inhabitants [4][5][6][7]. Such an opinion was originated from a relatively abundant occurrence of small solitary rusose corals in Tibet and