The MOC is the meridional-vertical circulation that affects redistribution of energy and global materials like fresh water, carbon, etc. Related studies show that MOC has strong implications for the long-term variation of ENSO, the position of the Intertropical Convergence Zone and the marine ecosystem, and further impacts long-term climate change. Deep SCS MOC is a good indication of the characteristics of deep circulation and is closely related to the freshwater and heat balance, and the sediment transport.