On the basis of the topography and historical seismic information of the South China Sea, many scholars at home, and abroad have investigated the source area of possible earthquakes and tsunamis on the South China Sea. In this study, on the basis of previous research results, the authors analyze the areas that may be a tsunami source, select a group of typical tsunami sources, simulate these tsunami sources with the COMCOT model, and assess the damage to coastal areas and reefs of the South China Sea from in terms of tsunami propagation time, wave height, and energy distribution. The sensitivity test confirmed that the intensity of the tsunami wave is considerably influenced by the magnitude of the earthquake. If a local tsunami is triggered by a strong earthquake, then it will cause considerable damage to different parts of the coastal areas and reefs of the South China Sea.