Numerous high- amplitude dipping reflections in the lower oceanic crust are developed in the East sub- basin (ESB) of the South China Sea (SCS), recording the process of oceanic crust accretion. Understanding the structure and genesis of these dipping reflections is crucial for comprehending the spreading process of the SCS. Based on multi- channel seismic profiles, this paper describes the structural features and internal deformation of these lower crustal dipping reflections (LCRs) in the ESB and discusses their genesis. Our results reveal high- amplitude LCRs in both the southern and northern parts of the ESB. Most reflectors terminate at the Moho reflection, but significant differences exist in their distribution range, structural features, and genesis between the two regions. The northern LCRs are longer (approximately 15~22 km) and wider (approximately 150 km north- south extent) than their southern counterparts (approximately 5~8 km long, approximately 70 km north- south extent). The depth of the Moho surface in the lower crust inclined reflection area shows obvious differences between north and south. The northern part displays a shallower Moho (approximately 0. 5 s), compared to the southern part (approximately 1.2 s). Further, the basement topography is flat in the north and rougher in the south. This suggests that the oceanic crust is thicker in the northern LCR area and thinner in the south, indicating an asymmetrical and heterogeneous process of oceanic crust accretion in the ESB. The genesis of the ESB' s LCR may be closely related to syn- magmatic faults, hydrothermal cycles, magmatic interstitial intrusion in the crust- mantle transition zone, and deep basement faults.