Abstract: South China Sea (SCS) is one of the largest marginal sea in the western Pacific Ocean. SCS large-scale currents (＞100 km) include seasonal wind-driven basin-scale currents, Kuroshio branches, SCS western boundary currents, and so on. Mesoscale process (10—100 km) in terms of eddies, fronts, upwelling and submesoscale process (1—10 km) are also active in SCS. The energy transformation among above multi-scale process plays vital roles in global oceanic energy balance. Some achievements are on the dynamic characteristics of SCS throughflow, continental shelf and slope currents, SCS western boundary current, the impact of SCS western boundary current on mesoscale eddies, and the influence of mesoscale eddies on turbulence, etc. Forward energy cascade process has been revealed that the SCS western boundary current releases its energy to mesoscale eddies via baroclinic instability, while the mesoscale eddies cascade energy to submesoscale process or smaller scale process through barotropic instability, in terms of shear instability. The issues of advanced observation of the energy transformation process among multi-scale motions, inverse energy cascade from small scale process to (sub)mesoscale process, and the contributions of submesoscale process to the SCS weather and climate remain unclear and merits near future study.