In the investigation of the regional ecosystem status, the combination of Remote Sensing (RS), Global Positioning System (GPS) and Geographical Information System (GIS) technologies can provide the dynamic data timely and visually. A database of ecosystem can be built based on the data with these technologies, and used for relevant departments of the state government to make rational decisions and planning. This paper describes a case study in Wenchuan District of the RS-GIS-GPS technologies in the policy-making process of changing cultivated land to forestry and in the management of the ecosystem monitor.