Abstract: The RS-GIS-GPS based grassland information system for Western China is an application sub-system of the RESOURCES AND ENVIRONMENTAL INFORMATION SERVICE SYSTEM FOR THE MINISTRY OF AGRICULTURE of China which is a national project supported by the Ministry of Science and Technology (1996～2000). The grassland information system is based on a GIS, and integrated with RS, statistics and ground monitoring data. The system design and implementation, a geographical and mathematical model for grassland classification development, a case study on the Western China's glass and animal balance analysis are introduced in this paper.