Abstract: The Zengmu Basin has been a hot spot in the Nansha area for research of hydrocarbon generation and exploitation. In order to assess the hydrocarbon resources potential in the basin, this paper made a comprehensively investigation on the tectonics and the characteristics of source rocks based on regional geology, seismic survey and drilling data. The main source rock of the Basin is the Oligocene and Miocene organic-bearing mudstone. It is estimated that the hydrocarbon resources of the basin is about 140.18×10⁸ t calculated upon the accumulation to discharge coefficient, of which 99.98×10⁸ t is located within the traditional boundaries of China. According to the tectonic characteristics and hydrocarbon geologic conditions, the Zengmu Basin could be further divided into three exploration areas on different grade. The Nankang platform and the west slope are both located in the most favorable exploration area.