The system is based on the Internet/Intranet, which can provide decision support for implementation of precision agriculture. As the key technologies of precision agriculture, GIS(Geographic Information System) and ES(Expert System) were studied and integrated into the system. From the system, users can get not only the geographic information of field to analyze fertility, but also the measure scheme about variety selection, fertilization, irrigation, prevention and control of plant diseases and elimination of pests, etc. The system is of stability and security, and can be maintained and used easily.