The generation, propagation and ï»¿dissipation of internal tides determine the energy distribution and mixing in the global ocean, and are also significantly affected by ï»¿the background currents and stratification. Circulations, eddies and the other oceanic phenomena in the South China Sea have multiple ï»¿spatial and temporal scales. Therefore, it’s necessary to illustrate ï»¿the impacts of the background field on the tidal energetics in the SCS. In this talk, we use the model output from the high-resolution (ï»?/48°) LLC4320 simulation of ï»¿MITgcm to reveal the tidal energy source and sink patterns in the SCS involving the impacts of the background field. Next, ï»¿the Sturm-Liouville equation, solved by a spectral method, is employed to investigate different responses of ï»¿internal tides in different modes, as well as to derive the energy decay scales ï»¿of internal tides. The results indicate that the background field can change the propagation of internal tides by changing the phase velocity as well as the ï»¿Doppler-shifted ï»¿frequency, and have different behaviors for the diurnal and semidiurnal components. In addition, ï»¿the parametric subharmonic instability— a way of weak wave-wave interactions, is firstly investigated in realistic ï»¿numerical simulation to validate the previous in situ observations and idealized simulations. ï»¿It is expected to have a fundamental contribution to the parameterizations of tidal mixing.