It is proved that a shallow Neogene Huangliu-Yinggehai gas play is developed in the central canyon in Lingshui Sag and its adjacent area in Qiongdongnan Basin. The deep Oligocene Yacheng coal series is the major matured source rock in the sag, which provides abundant hydrocarbon to the south part of the sag. Fan delta, turbidite channel and submarine fan facies sandstone reservoirs are developed in the Upper Oligocene Lingshui 1st Member Formation and the Lower Miocene Sanya 2nd Member. Main controlling factors of sand body enrichment are contributed to the boundary fault transfer belt, faulted terrace belt and structural slope-break belts. Hydrocarbon accumulation pattern is described as getting close to source rock, migrating in vertical and lateral directions and gathering in the later period. On account of the conditions including reservoir, migration and traps, it is optimized that the reverse faulted terrace belt in the slope of southern Lingshui sag is the areas favorable for exploration.