Abstract: A torrential rainfall came to Kumamoto prefecture of Japan in mid-July 2012,which initialed floods in the main city area and countless geologic hazards in Aso. They mainly include slope failures, landslides and mud-rock flows. The geographical environment there added too much inconvenience to the restoration work conducted by the related department. Thus compared to the operation of restoration work afterwards, erection of protective facilities in the potentially dangerous area prone to geologic hazards before-hand seems more practical and economical. RESS,risk evaluation system for slope failure based on geographical data base, developed independently by the Department of Civil and Environmental Engineering in Kumamoto University. Seven categories, relief energy, cross section, slope angle, water catchment, land use, geology, change of hazards location, together with risk evaluation were resolved in the forms of data and three-dimensional images. Quantification Theory Ⅱ method then was used to calculate and evaluate the potential risk of the Sakanashi area in Aso. Both the accuracy ratio of risk evaluation and hazards location discrimination were the research requirements. Finally a hazards map of the studied area for prediction was able to be plotted, in which the dangerous locations were marked out clearly by different colors, and which consequently is easy to be understood and be accepted by both the public and professionals.