Application and research of GIS in the slope engineering is one of the hot topics in this field. In this paper, the fuzzy comprehensive evaluation method of slope stability based on GIS was researched. It developed and set up a multi factor slope fuzzy comprehensive evaluation system by using slope database and can quantitatively classify and evaluate the slope stability in a quick and efficient way. This system can be at work on slope data management, inquiry, statistics and spatial analysis. It evaluated the fatality and vulnerability to the slope of a large scale coal mine as an example.