Abstract: Việt Nam Cát Bà island is area developed Carboniferous Visean stage reef on the world rare in neonatal animal of framework reef, the coral reef of main part by group rugose coral Donophyllum sp. and Thysanophyllum sp. etc. built, make up the framework corals similar but all by fasciculate and corniform two types developed forms. Reef continuous developed, did not form a distinct gap and period characteristics, reef distribution has certain evolution trend; and within the layers of coral but without the development of evolution characteristics, identify three consecutive biological stage, i.e. plexiform Donophyllum sp. developmental stages, the columnar Donophyllum sp. development stage and columnar Thysanophyllum sp. developmental stages, of reef rock profile micro phase characteristics of that divide out the mud bioclastic packstone and coral lattice frame barrier product rocks, bioclastic grainstone and can identify the three types of sedimentary facies. In the development process of the reef, the reef facies, reef and shoal facies are experienced by the open platform, reef platform, and shallow platform.