The purpose of this paper is to explain the flood disasters caused by Typhoon Morokat. The related information is combined by collecting data and investigation. The scale of flood caused by Typhoon Morokat is very huge. The south Taiwan (Taichung-Pingtong) is affected and the serious disaster areas are Chiayi, Tainan, Kaohsiung, and Pington. According to the investigation and analysis, all these disasters are related to the enormous rainfall in Typhoon Morokat. The disaster style is inner water problem in the past, but outer water problems (levee break, overbank flow) are in Typhoon Morokat. The reason of levee break is related to the high-density sediment laded flow and drift woods from the upstream basin. It proves that flood caused by Typhoon Morokat is a whole-watershed problem.