In response to the flood disaster caused by extreme rainfall, using rainfall forecast for flood warnings plays an important role in disaster management. This study takes Typhoon Soudelor as an example, by applying QPESUMS observation and WRF forecast data, rainfall intensity in Wulai area, river water level in Taipei area, and the flood situation Yilan area, are statistically analyzed and physically modeled. The results show that rainfall forecast can effectively predict the occurrence of flood disasters and provide sufficient warning time, playing as a valuable reference for disaster response and management.