Consumer-grade global positioning system (GPS) becomes common and popular in these days because of its low cost along with acceptable accuracy. a GPS receiver cannot always obtain precise position because it affected by errors from either satellites or the receiver itself. Many researchers proposed effective approaches to improve positioning accuracy of GPS receivers. in this paper, we propose a method based on the concept of differential correction using two consumer-grade GPS receivers and genetic programming (GP). the proposed method generates a correction function through GPS information gathered by GPS receivers and a known position. any GPS receiver which transfers NMEA (National Marine Electronics Association) sentence information can be used for the proposed method. the method could be implemented on various GPS-embedded devices without modifying hardware components.