Abstract: The Pearl River Mouth Basin is a basin with the characteristics of variable geothermal field, firstly presented as a fault transforming into depression later, transferring from land to sea. In this basin, three sets of source rocks are developed, i.e., Wenchang Formation, Enping Formation and Zhuhai Formation. Based on the analysis and test on a large number of source rock samples in combination with experimental analysis, geological analysis and geological simulation, this study conducts a comprehensive grading evaluation on the development characteristics of the three sets of source rocks and the thermal evolution history, hydrocarbon generation history and resource potential of the depression/half graben/sag. The research indicates that (1)the lacustrine oil-prone source rocks in Wenchang Formation during the mid-early rifting stage are the chief source rocks in this region, while the coal-measure oil-gas-bearing source rocks in Enping Formation during the late rifting stage are important source rocks in this region. Only in Baiyun sag, the marine terrigenous oil-gas-bearing source rocks in Zhuhai Formation during the depression stage entered the hydrocarbon generation threshold. (2)The geothermal gradients increased from shallow area to deep-water, which resulted in the fact that maturity threshold and hydrocarbon generation window were located in the water area rapidly becoming shallow. In the shallow area, source rocks were developed in the mature-high maturity stage, characterized with late hydrocarbon generation. The main hydrocarbon generation period was from 16 Ma to the present. In the deep water, source rocks are in the mature-over mature stage, and Baiyun sag is characterized with early hydrocarbon generation with the main hydrocarbon generation period of 33-0 Ma. (3)The total geological resource of Pearl River Mouth Basin is about 85×10⁸ tons through assessment. It is rich in oil and gas resources, where the shallow water area is dominated by petroleum resources, equivalent with the oil and gas resources in the deep water area. (4)According to the evaluation criteria of offshore hydrocarbon-generation depression, Huizhou, Baiyun, Lufeng, Xijiang, and Enping sags are hydrocarbon-rich depressions, and Kaiping and Liwan sags are moderate hydrocarbon generation depressions with favorable exploration potential.