Abstract: In order to make good use of agricultural resources, and realize the convenient and digital crop production management, a knowledge model and PDA-based precision farming system was established on the platform of Microsoft Visual Studio.NET 2003, based on the existing crop management knowledge model, and by integrating the technologies of PDA, embedded-GIS and GPS. The system not only realized the functions such as pre-sowing (or transplanting) cultural plan design, suitable dynamic indices design, and real-time regulation based on crop growth status, but also had the functions as map handling, location and navigation, spatial data collection and information management. In 2007, the system was carried out in the rice production region of Wujiang City, Jiangsu Province. The application result indicated that the average rice yield in the experimental fields with precision management plans recommended by the system was 9 196.9 kg/hm2, with 7.43% increasing production and 7.5 kg/hm2 decreasing nitrogen rate, as compared with the traditional cultural plans. This system provides a new service platform for crop precision farming management, and greatly improves the practicability of precision farming technology.