Abstract: Reefs are favorable for petroleum accumulation and their inner structure and generation environment have been the study focuses of geologists.Studies of the structure of the carbonate platform margin of the southern uplift of the western deep-water region of the South China Sea have indicated that,there are 2 types of platform margin structure (symmetrical and asymmetrical) and 3 types of platform margin style (fault-controlling,faulted flexure and carbonate ramp).Based on the analyses of seismic profiles,the generation styles and features of reef controlled by different platform margin structures have been studied.The structures of carbonate platform margin and the characteristics of reef are mainly controlled by regional tectonic differences,palaeogeomorphologies,ancient monsoons and sea level changes.