Abstract: Similar to those of the middle and small basins of continental margin facies in South China, the basement of the Beibu Gulf Basin has experienced 3 evolutionary stages: rift from Paleocene to Eocene, rift to depression transition during Oligocene, and regional subsidence ever since Miocene. Influenced by the basin-forming events such as Shenhu, Zhuqiong, Nanhai and Dongsha, 4 periods of faults developed in the Fushan and Maichen sags in the southeast of the basin, resulting in 3 dominant fault systems of NE,NEE and NW directions, forming 2 tectonic layers. The faults are of flower, piled flower, petal and bush shapes, forming 4 styles including basal tilted strike-slip, basal stretch Domino, cap extensional detachment and cap sliding traction. The Fushan Sag showed an obvious asymmetric stretching process, forming NE-oriented tectonic transfer zone in the middle. The EW-oriented fault system of stage Ⅳ in the southeast of the basin controlled present oil reservoirs in the 2 sags. The nose-like structural zone in the center and the steep slope step zone in the southeast of the Fushan Sag are favorable petroleum exploration targets in the southeast of the basin.