The inteal seismic architectures of the Middle Miocene in Beikang Basin,southe South China Sea,were investigated and described using regional 2D seismic data from Guangzhou Marine Geology Survey.In particular,five typical seismic facies were identified based on an integrated analysis of the amplitude,continuity,contact relationship,and morphologies of seismic reflections.Bathyal-abyssal fine-grained sediments,deltaic front sandy bodies,turbidites,and small-scale turbidite channels were developed in the Middle Miocene according to the tectonic-sedimentary evolution of the sedimentary basins in the southe South China Sea.The findings of this study suggest that deltaic front sandy bodies and turbidites can be considered as the two major types of deep-water clastic reservoirs for the depression stage of Beikang Basin.A well-developed source-reservoir-cap assemblage was composed by deep rift-stage source rocks,deep-water clastic reservoirs of the Middle Miocene,and bathyal-abyssal deep-water fine-grained sediments after the Middle Miocene,implying a good potential for hydrocarbon exploration.