Based on analysis of drilled and seismic data, the large early Miocene carbonate platform margin is distributed along a ring-shaped area from Well L7 to Well H6 and to Well F1 in Dongsha Uplift, Zhujiangkou Basin. On account of slope geometry and sedimentary filling characteristics, the platform margin can be divided into four zones, i.e. the southeast, the center-south, the west and north zones, each of which displays their own different condition of hydrocarbon accumulation. The slope is wide and steep and reef-shoals widely develop in the southeast zone where oil exploration will face some risk due to lack of effective sandbodies to conduct with the underlying strata although it is near hydrocarbon-rich Baiyun Sag. The slope is not so wide and steep but reef-shoal also widely develops in the center-south zone where the reef-shoals near ridges maybe are the favorable exploration targets. The slope is gentle but not wide and bioclast shoals develop in the west zone where the structural-lithologic traps that are distributed along structure ridges should be the breakthrough targets as the center-south zone. In the north zone, the slope gets small and reef shoals do not develop because of locating in leeward so that the small-scaled bioclast shoals adjacent to Huizhou Sag maybe is of exploration potential.