In recent years, rainfall-induced landslides in Taiwan have been centralized in hillslope areas with slopes of 30°-60°. Moreover, based on the analysis of landslides caused by typhoons Mindulle and Aere in 2004 in three watersheds in northern, central, and southern Taiwan, increasing cases of small landslides have mainly been induced by the scour during floods. The major inducing factor for the landslides in the Shihmen watershed and Kaoping upstream watersheds was heavy rainfall. In contrast, the main factors in the upstream of the Dajia river watershed were the influence of 1999 Chichi earthquake, the fragile geology and the steep slope. The landslide ratio caused by Typhoon Morakot in 2009 in the upstream of the Kaoping watershed was around 7.3%, and the serious landslide cases with expanding areas were mainly located in areas with concave topography and high accumulated rainfall.