On September 21, 1999, Taiwan was struck by the devastating Chi-Chi earthquake, which damaged Yushan National Park. This study focuses on tourism demand (i.e. the number of arrivals) after the September 21 earthquake in Taiwan. This study uses the Grey model and regression to forecast tourism demand for Yushan National Park. Monthly tourism demand found to change as the result of seasonal differences. According to the analysis presented in this study, Seasonal Grey forecasting seems to be the best method for forecasting tourism demand. This study investigates three forecasting methods that show a rising trend for tourism demand in Yushan national park , subsequently Yushan national park headquarters can perform better tourism strategic planning.