Abstract: The discovery of natural gas in the Enping 17 Sub-sag has opened up new frontiers for natural gas exploration in the shallow waters of the Pearl River Mouth Basin. Systematic understanding of the gas generation potential of the Wenchang Formation source rocks and the origin of natural gas in the Enping 17 Sub-sag is lacking, which has severely constrained deep-layer exploration planning. To address this knowledge gap, this study integrates geochemical analysis and simulation techniques to comprehensively evaluate source rock characteristics and gas generation processes. Key results reveal the Wenchang Formation comprises two distinct source rocks units: The lower Wenchang Formation is dominated by semi-deep to deep lacustrine facies high-quality source rocks, characterized by high sapropelic and exinite group maceral content, these rocks formed in reducing environments under humid climatic conditions with abundant aquatic vegetation and favorable water column nutrient levels. The upper Wenchang Formation is primarily shallow lacustrine facies source rocks with dominant terrigenous organic input, characterized by high vitrinite group maceral content, indicating a relatively deteriorated lacustrine environment. Geochemical signatures of natural gas esindicate a low-maturity, which is from both Wenchang and Enping Formations, mixed-origin kerogen cracking gas. This confirms a dual contribution from both Wenchang source rocks units. Semi-Deep/Deep Lacustrine Facies source rocks exhibit an “oil-generation window is concentrated, followed by late-stage explosive gas generation” profile. Shallow Lacustrine Facies source rocks possess a "broad-window, continuous gas generation" capability. This study has elucidated the origin and sources of natural gas in the Enping 17 Sag, quantified the gas-generating potential of source rocks, identified semi-deep to deep lacustrine source rocks as the primary gas-bearing source rocks and shallow lacustrine source rocks as significant supplementary gas-bearing sources, and provided critical scientific foundations for optimizing exploration targets in the region. The findings offer significant application significance for exploring analogous sags in the shallow-water areas of the Pearl River Mouth Basin.