Wu and Tachia River watersheds are located in the middle of central western Taiwan. The topography includes seashore, plain, hill and high mountain. Total area of Wu and Tachia River watersheds is 3260 km^2. We investigated, classified and mapped the vegetation of these areas during 2003-2007. The data of 495 plots (400 km^2 each) were analyzed and the rare vascular plant information were established using GPS and GIS technologies. Totally 1028 rare plant locations were recorded. The rare plants consist of 195 taxa, belonging to 77 families and 157 genera. There are 40 pteridophytes, 10 gymnosperms and 145 angiosperms in which 114 are dicotyledons and 31 are monocotyledons.