Abstract: Combing studies in sequence stratigraphy, growth strata, tectonic evolution, denudation transformation, seismic facies, and sedimentary facies, we summarized the technology for identification of hydrocarbon source rock applicable for reformed sags in the case of the Xijiang Main Sag of the Pearl River Mouth Faulted Basin. Based on the growth stratigraphy, tectonic evolution, and erosion history, differential tectonic activities were characterized at different locations of the sag in the sequence framework, on which the spatial distribution of source rocks were qualitatively predicted in perspective of differential tectonics and sedimentation. Meanwhile, considering the structural parameters controlling the distribution breadth and sediment thickness in the half-graben basins, an equation was established to semi-quantitatively calculate the tendency of variation of hydrocarbon source scale vs the strikes of controlling faults. In addition, the results of semi-quantitative calculation and qualitative analysis were compared and testified each other, from which a set of hydrocarbon source identification technology were proposed to evaluate the source rocks in the Xijiang Main Sag, and good results have been achieved.