The Cenozoic reef-banks reservoir in Qiongdongnan(琼东南) basin is one of the most profitable targets worthy of prospecting in the deep water area of the northwestern South China Sea.In this study,the characteristics of organic reef-like reflectors in southern uplift area of Qiongdongnan basin are analyzed based on the latest 2D and 3D seismic data.It is found that reef-like reflectors in Qiongdongnan basin show high-amplitude moundy continuous reflection at the top and the bottom,chaotic reflection inside the reef-like reflector and there is obviously speed difference between reef-like reflector body and surrounding rock.Combining the geological setting of reef and comparative analysis,the reef-like reflectors are considered to be the reef-banks.Furthermore,the results show that there are three kinds of reef structures in the southern uplift area of Qiongdongnan basin:the fault controlling structure,the fault flexure structure and the carbonate ramp structure.Each structure has its own grow-units that can reveal the growth process of the reef in order.The distribution of reef-like reflectors in space shows an arc belt pattern.According to this,four reef arc belts are identified,and their spatial trends are thought to have a good relationship with the buried fault.The internal structure constitution and the growth state of reef-like reflectors are mainly controlled by the geomorphology and monsoon-ocean current.The result has an instructive significance to oil-gas exploration of organic reef not only in Qiongdongnan basin,but also even in deep water areas of the South China Sea. The Cenozoic reef-banks reservoir in Qiongdongnan (Qiongdongnan) basin is one of the most profitable targets worthy of prospecting in the deep water area of ​​the northwestern South China Sea. In this study, the characteristics of organic reef-like reflectors in southern uplift area of ​​Qiongdongnan basin are analyzed based on the latest 2D and 3D seismic data. It is found that reef-like reflectors in Qiongdongnan basin show high-amplitude moundy continuous reflection at the top and the bottom, chaotic reflections inside the reef-like reflector and there is obviously speed difference between reef-like reflector body and surrounding rock. Combining the geological setting of reef and comparative analysis, the reef-like reflectors are considered to be the reef-banks.Furthermore, the results show that there are three kinds of of reef structures in the southern uplift area of ​​Qiongdongnan basin: the fault controlling structure, the fault flexure structure and the carbonate ramp structure. Each structure has its own grow-units that can reveal the growth process of the reef in order. the distribution of reef-like reflectors in space shows an arc belt pattern. Accredited to this, four reef arc belts are identified, and their spatial trends are thought to have a good relationship with the buried fault. internal structure constitution and the growth state of reef-like reflectors are mainly controlled by the geomorphology and monsoon-ocean current. The result has an instructive significance to oil-gas exploration of organic reef not only in. Qiongdongnan basin, but also even in deep water areas of the South China Sea.