The explosion of the AZF chemical plant in Toulouse, on 21 September 2001, dramatically revealed an old problem of industrialised era that is the vicinity of industrial plants and urban areas. With the 30th July 2003 new law (n° 2003-699), in particular with the Technological Risk Prevention Plans (TRPP), stakeholders can't now ignore the importance of territory in risk assessment. The objective is to identify major stakes for the society and their vulnerability for a better land use planning. But this method needs analytical and synthetic tools, as GIS (Geographic Information System). Indeed, GIS permits experts to structure the data and enables them a spatial lecture of risks. So stakeholders can see and have a concrete representation of risks on their territory, and maps become common discussion and negotiation tools. But that requires understanding in what risk space-rating and mapping need an interdisciplinary vision and a global approach of a same territory. In the context of a PhD study in collaboration with INERIS and the research laboratory GEOSYSCOM, we try to develop a methodology for major industrial risks assessment, based on map and spatial analysis allowed by GIS.