Abstract: As an important hydrocarbon-rich depression in the Zhuyi Depression of the Pearl River Estuary Basin, the geometric features and genesis mechanism of the Huizhou sag are of key significance for hydrocarbon exploration and development. Based on high-precision 3D seismic data and seismic line analysis, this paper systematically analyses the planar and sectional geometric features of different levels of fractures in the Huizhou Sag on the basis of previous studies and in the context of the tectonic evolution of the region, and explores the differences in the genesis of fractures with different orientations, and their impact on oil and gas formation and reservoirs. The study shows that: (1) the fractures in the study area are mainly extensional normal faults, which can be roughly divided into three levels. In profile, the first grade fractures are typical of high-angle shovel-type, plate-type and slope-ping-type, while the second and third grade fractures are mostly upright plate-type, and the combination styles are Y-shaped, domino-type, X-shaped, herringbone, and zig-zag. (2) On the plane, the first level of fractures are orientated towards NE, NW and near EW, spreading in a right-handed diagonal column; the second level of fractures are mainly orientated towards NW, and the third level of fractures are mainly orientated towards NW and near EW, spreading in a geese column. (3) The fracture system is controlled by the succession of basement fractures and the superposition of multi-period stress field. During the Yanshan period, the NE-SW oriented basement fractures were activated to form NE and NW oriented fractures; during the late rift period, the rotation of the stress field induced the development of near EW oriented fractures; and during the tectonic activation period, the fractures were superimposed on the dextral strike-slip modification. (4) NE-directed fractures dominated the early vertical transport, EW-directed fractures drove the late reservoir formation, and NW-directed fractures regulated the trap formation. The research results reveal the control mechanism of multi-phase tectonic activities on the geometric features of fractures, which will provide scientific basis for the future exploration and development of oil and gas resources in Huizhou Sag.