About the software of numerical model, countries to develop model must be base on their main local coast. And the parameters of the software will be built to fit their local coast. But coast are different from every countries. If use the parameters to simulation in Taiwan, the result may be wrong. The study of this paper use SMC(coastal modeling system). To match up different kind of parameters, such as wave¡Bperiod¡Btide to simulate. Search and collect the data on the study of local area over the years. Although first to confer the change of bathymetry on Sizihwan, which influence on the wave of typhoon and monsoon. To understand the bathymetry influence on different type of waves. Then simulate the change of the sea bed by the module of SMC ' Mopla. And compare the result of simulate and the measurement, to probe into the change of bathymetry. The influence of the waves of southwest monsoon on Sizihwan, the characteristic was erosion close-shore and accretion off-shore on the beach. The influence of the waves of northwest monsoon, the characteristic was wave induce the berm. There are best result of simulate the waves of southwest monsoon, but bad at the waves of northwest monsoon.