<p>The Zhujiang (Pearl) River Mouth Basin (PRMB) is located in the northern part of the South China Sea, and it is one of China’s three major offshore hydrocarbon-rich basins, playing an indispensable role in meeting the country’s energy needs. Exploration for oil in the PRMB started early and has achieved remarkable results in some sags, but many sags have yet to yield significant discoveries, necessitating the search for new favorable exploration areas. The aim of this study is to analyze the deep structural characteristics of various sags in the PRMB and predict favorable exploration areas, providing corresponding support for the next strategic breakthrough in oil exploration. Some studies indicate a certain relationship between the Moho depth and crustal thickness and the occurrence of oil. In this paper, based on satellite altimetry gravity anomaly data, we utilize a Moho depth inversion method based on variable residual crustal density to obtain the Moho depth in the PRMB, from which the crustal thickness and crustal stretching factor of the basin are calculated. The results show that the Moho depth in the PRMB ranges from 10 km to 37 km, the crustal thickness ranges from 7 km to 35 km, and the crustal stretching factor ranges from 0.9 to 3.0. Finally, we propose a comprehensive evaluation scheme for oil resoureces based on the CRiteria Importance Through Intercriteria Correlation (CRITIC) method, which comprehensively evaluates multiple factors, such as the Cenozoic sedimentary filling scale, Cenozoic thickness, Moho depth, crustal thickness, and crustal stretching factor, and provides evaluation criteria for identifying hydrocarbon-rich sags. According to this evaluation scheme, the exploration potential is relatively high in the Liwan Sag, Jinghai Sag, Heshan Sag, and Jieyang Sag, which are favorable exploration areas.</p>