The area of Quang Tri province is a medium level, but the fact that its mountainous topography occupies over 70 percent area, forest cover is destroyed due to war along with concentrated heavy rain, human activity are making the flashflood hazard increase in scale and intensity. Application GIS to establish flashflood hazard map is quantitative approach and high reliability. This article has established flashflood hazard map in scale 1/100.000 of Quang Tri province. In the database of map have defined high level flashflood hazard districts includes Huong Hoa and Dakrong
the medium level flashflood hazard includes five districsts: Vinh Linh. Gio Linh, Hai Lang, Cam Lo and Trieu Phong
Dong Ha city and Quang Tri town have been low and very low level flashflood hazard.