Typhoon waves play a major role in engineering and environmental problems. Our long-term goal is to investigate variability and trends of typhoon waves over past 62 years. However, the parameters in numerical wave models need to be calibrated before a model can be applied to a specific region. In this paper, we selected the 3 most important parameters from the source term of the SWAN wave model and subjected them to sensitivity analysis to determine which parameter is the most sensitive. After sensitivity analysis, we adopted the ARS method to find the optimal value of the parameter to which the SWAN wave model is the most sensitive by comparing modeling results with observed data at three buoys off the northeastern coastal waters of Taiwan; the aim being to find optimal value of the parameter for improved modeling of wave development. The procedure adopting the optimal parameter in wave simulations did improve the accuracy of the SWAN wave model in comparison to default runs based on field observations at three buoys.