In this paper we aim to develop a location-allocation model for the school emergency shelter selection by using GIS. Through the studies of emergency shelter in recently years, a location-allocation model for school emergency shelter selection is proposed. Based on location-allocation model theory, the optimal evacuation model for school emergency shelter selection is made with constrains of the largest site service capacity and the shortest network distance. In the process of the model construction, we take school emergency shelter's safety and suitability into full consideration. According to the characteristics of this model, the environmental constraints model is constructed to make spatial overlay analysis of six factors by using ArcGIS 9.3. The six factors are terrain slope, rivers and lakes, earthquake fault zone, flammable and explosive site, collapsed range of High-rise buildings, and protection range of cultural relics. The environmental constraints model respectively discusses the five factors influence range when the earthquake happens. And the actual capacity of the evacuation demand and site supply is calculated in this way. In order to reduce the error, the straight-line distance as the evacuation path is not chosen in this paper. Through the network analysis of the unaffected road, the shortest evacuation road is found. Considering the largest site service capacity and the shortest network distance, is the key to solve the problem. By introducing the location-allocation model theory, the solution of the optimal evacuation model is obtained to select the school emergency shelter. In this paper, school emergency shelter in Xicheng District of Beijing City is selected by using this technical method which can effectively solve the problem of school emergency shelter selection. This optimization method is an effective measure to prevent the school from disaster and provide safe site for the student. This academic technology is introduced as the references to relevant researchers on the school emergency shelter selection.