Abstract: Based on the studies of fault sealing evolution, oil-bearing formation and hydrocarbon generation ability of highly-conductive mudstones in the Dainan Formation, the fault-lithologic reservoir systems of the Dainan Formation in the Gaoyou Sag have been classified into 3 types, including self-sourced, other-sourced and mixed-sourced. The self-sourced accumulation systems mainly locate in the deep Shaobo and Fanchuan Sags, and the Shaoshen1 resrvoir is typical. The other-sourced accumulation systems mainly distribute in the Majiazui, Zhou22 and Shao18 reservoirs. The mixed-sourced accumulation systems are represented by the Lian3, Lian7 and Yong22 reservoirs. The fault-lithologic reservoirs of the Dainan Formation in the Gaoyou Sag are controlled by2 elements, oil source and migration pathway. The favorable zones for exploration include Huangjue-Majiazui, Lianmengzhuang-Yongan and Caozhuang-Xiaoliuzhuang.