Abstract:In Taiwan historically,a dense population has developed on the western plain area of the country.Gradually,the hillsides are being occupied by more people who threaten to the natural soil and water(resources).The geologic mountain range of Taiwan mostly exists consists of deposit sedimentary rock and metamorphic rock,and its property is fragile and apt to rupture.In addition,the annual average rainfall pricipatation is around up to 2?500?mm,of which 78% falls from May to October in the typhoon season.The combination of these environmental circumstances frequently causes debris flows in the upland areas of Taiwan.Collected Studies about debris flow events had gathered to classify and describe the situation in Taiwan.The following topics will order by characteristics of debris flows,analysis of debris flow constituents,risks evaluation and(reconstruction),engineering for counter measurements and investigations simulation of investigations simulation in situation.