Abstract: The objective of this study is to use advanced electronic andcomputer technology to design a practical and economicalvariable rate irrigation control system according to the actual conditions in rural areas of China. The control system integrates single-chip micyoco(SCM) technology, Global Positioning System(GPS) and Geographic Information System(GIS). The main hardwareand software components of the system include an AT89C51 single-chip unit as the microprocessor, an IC(Integrated Circuit) cardused to transfer GIS information in the unit, and a GPS receiver based on Jupiter GPS OEM developed independently. Meanwhile, asimple and quick data-querying algorithm based on the vector method was put forward and used in the system. The control systemreceived position information from the GPS OEM, recognized the site and determined the vehicle position in the field. Then, theamount of water to be applied was found from a water prescription map on the ICcard based on the position data, and the water flowrate was calculated based on vehicle speed and the spray width. Finally, the flow information was converted to an electronic signal todrive a water-regulating valve on an irrigation machine to accomplish variablerate irrigation. The experiment results in field andlaboratory showed that there was approximate accuracy for the low cost GPS OEM receiver self-developed compared with Tramble AgGPS132, and the control system was able to fulfill variable rate irrigation automatically based on a prescription map or to apply a specified amount of water through manual control.