Several medium to large gas fields have been discovered in the deep- water area of the Qiongdongnan Basin, but their accumulation mechanism and dynamic process are still in dispute and have constrain oil and gas exploration in this area. Through organic geochemical and structural geology methods this study analyzed and investigated the distribution of Yinggehai and Huangliu Formation reservoirs, gas maturity/origin and possible accumulation mechanisms in the central canyon gas fields. Geochemical and geological results show that natural gases are mainly derived from type III kerogens, and their possible source rocks are the prodelta and neritic mudstones of Yacheng Formation in Ledong- Lingshui sag. Extensive distribution of turbidite channels of Yinggehai and Huangliu formations, accumulation and cap assemblages and pressure features effectively control multiple sequential charging process and accumulation- escape balance, with local structure highs controlling the scale of the gas pool. Anomalous high- pressure in the deep part of Ledong and Lingshui sags provides adequate driving force and migration channels for large accumulation, and the vertical pressure compartment and regional cap rock have controlled the sequences for gas accumulation. The natural gas accumulation in the central canyon is characteristic of vertical- lateral migration and composite accumulation of average pressure and excess pressure zone. Strong structural deformation is favorable for rapid releasing of pressure and fluids. Diapir uplifting and canyon incision shows a mirror- like relationship, resulting in a big remnant pressure gradient and thus forming high efficient migration pathways. Based on this new accumulation model, this study proposes that the structural traps of the Meishan Formation below the central canyon, the traps in the Lingnanslope and the low uplift of Songnan could be new exploration targets for large to medium gas fields in the deep- water area.