Abstract: Forest fire is a kind of natural disaster with strong suddenness, great destructiveness and difficulty in treatment and rescue. In this paper, Xichang City in Liangshan Prefecture of Sichuan Province was taken as an example. Based on GIS technology and DEM data, a real-time prediction method of forest fire was proposed. Combined with NDVI, atmospheric humidity, surface temperature and vegetation type, the forest fire risk grade of the study area was quantitatively evaluated, and the fire risk was divided into five grades. The distribution map of forest fire danger in the study area was made by ArcGIS software, in order to discover the fire in time, reduce the damage of forest vegetation, and reduce the economic losses and casualties caused by forest fire.