We consider a method to update tsunami database in order to enhance the capability of Malaysia National Tsunami Early Warning System. We identify the Manila trench to be the location of potential earthquake sources which can generate a hazardous tsunami in South China Sea region and the surrounding countries including Malaysia. The source points are located along the Manila trench with 4 depths (0, 10, 20 and 30 km). Fault parameters are set using a scaling law for 3 magnitudes (Mw 7.5, 8.0 and 8.5). Numerical simulations of tsunami propagation for 108 cases are performed using a software called TUNAMI-N2. Our target area is the coastal region of the east part of Malaysia, and forecast points are set along this area. There are two groups of forecast points; forecast points with a fixed distance of 5 arc-minutes and forecast points along the bathymetry contour depth of 50 m. The Green’s law is applied in order to estimate reliable tsunami heights for the coastal area. The results of the tsunami simulation showed similar tsunami waveforms pattern between the source points with the same earthquake scenario. In terms of tsunami amplitude, the results indicate that higher tsunami heights is originated from the source point with larger magnitudes. The factor of depth at the source point also could contribute to the amplitude of tsunami height. This can be explained by the condition of ocean bottom deformation. Finally, all the results will be additional information for the purpose to update tsunami database.