Abstract: Aiming at the questions such as excess N application, low N utilization rate at the season in the process of rice production, Decision Support System of precise N application in rice in Jiangyan city based on PDA was developed primarily. To meet with Precise N application in soil and PDA characteristics and according to exploiting PDA memory ability, the system was a suit of agricultural application software of PDA production（V1.0）, which was based on Windows Mobile, Embedded Visual Basic 3.0, ArcGIS 9.2 and integrated GPS module. The system integrated many functions such as real-time location, attribute data query based on the thematic map, precise N application decision-making according to the soil, study and tutor and so on, the users were very satisfied with it in practice.