From remote sensing images, it is found that the internal wave spreads from deep sea, by shelf slope, to shallow sea in the South Chinese sea. Because of the different environmental conditions and model applicabilities, it is the best to use two models to simulate the spread of ocean internal waves in deep or shallow sea. The spread of waves in deep sea is simulated with the nonlinear Schrdinger (NLS) equation first and then the spread of wave in shallow sea is simulated with the extended Korteweg de Vries (EKdV) equation by differential mathod. It can be found that the results are in good agreement with the actual remote sensing images, compared with those obtained by single model which consists of the NLS equation or the EKdV equation.