In this paper, the authors summarized the global spatial distribution of ridges and the sea basins which are formed by propagating rifting and spreading, and also gave a comparison between the gulf of Aden and the southwestern sub-basin.Through the comparison of the origin and the characteristics of the spreading center, volcanic activities, magnetic anomalies and so on, the authors proposed a new view of the tectonic evolution of the southwestern sub-basin, and the authors also found new evidence for the tectonic evolution of the South China Sea.