Abstract: The study of continental margins is the key to the reconstruction of plate tectonic movement, the investigation of Earth's environment and the development of mineral resources. The volcanic passive margin and magma-poor passive margin are the two basic types of passive margins. Although there are similarities in structure, evolution and ocean-continent transitional zone, the mechanism, tectonic processes and sedimentary characteristics are significantly different in the two types of passive margins. The Seaward Dipping Reflectors Sequences (SDRS) and the high-speed abnormal body below are the typical signs of the volcanic passive margin, while a low angle detachment fault (S reflector surface) is the main indicator of the magma-poor passive margin. The tectonics of the South China Sea is very complicated because it is located in the juncture of the Tethyan and ancient Pacific Ocean tectonic domains. The tectonic behavior of the northern margin of South China Sea has remained as the focus of hot debate among scholars. Based on the researches of typical passive margins abroad, comprehensive multi-scale tectonic research and numerical simulation were suggested as effective means to better understand the tectonics of the northern margin of the South China Sea.